# clinchers vs. tubular



## robbob (Aug 26, 2004)

what are the advantages of clincher vs tubular - I was looking at picking up some Ksyriums on e-bay and have noticed the tubular costs much less... Whats the dif???

Thanks


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## ultimobici (Jul 16, 2005)

robbob said:


> what are the advantages of clincher vs tubular - I was looking at picking up some Ksyriums on e-bay and have noticed the tubular costs much less... Whats the dif???
> 
> Thanks


Wheels are lighter & tyres are lighter. Due to nearly all of the air pocket being above the rim tubulars are more comfortable & handle better.

But, if you flat, they're more hassle. Repairs are fiddly, unless you use Tufo's with their own sealant. This can work on other makes, but not as effectively. Tufo's have the tube, casing & tread vulcanised together so they seal more easily. This can affect the suppleness of the tyre, so they aren't the most plush of tubs to ride.

www.tufo.com


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## ultimobici (Jul 16, 2005)

Forgot to mention, if you do flat on tubs, you can ride them flat although it's not good for the rim.


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## ru1-2cycle (Jan 7, 2006)

Yes...your spokes will get all loose and the rim may get permanent damage.


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## FTF (Aug 5, 2003)

ru1-2cycle said:


> Yes...your spokes will get all loose and the rim may get permanent damage.


Yeah, but if your in a crit, you can just keep going until you get to the wheel pit.


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## Mark McM (Jun 18, 2005)

*Counterpoint*



ultimobici said:


> Wheels are lighter & tyres are lighter.


For comparable strength and durability, tubular rims are lighter, but tires are really about the same weight. (Actually, tubular tires are heavier, but that's only because the weight includes the tube inside. Combined weight of tire and tube of kevlar bead clinchers are about the same as for tubulars.)

On the minus side, tubulars have been demonstrated to generally have higher rolling resistance than clinchers (all else being equal).



ultimobici said:


> Due to nearly all of the air pocket being above the rim tubulars are more comfortable & handle better.


But on the other hand, clinchers have a larger total air pocket, since it extends into the rim. Comfort is a matter of personal perception, but I haven't seen anything to indicate that there truly is a real difference in handling. Some of the best bike handling riders I know ride clinchers exclusively.


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## jroden (Jun 15, 2004)

If you have not been around the barn with tubulars and have no real need for them, I'd steer clear. the tires are costly, difficult to repair, require special glue to mount, will fall off when cornering if not mounted correctly and don't really perform all that much better than a good clincher with a latex tube. I ride tubulars, but can't really suggest that someone new to them should go down that road. The one exception is cyclocross, they are a good thing for that event, sort of.


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## Dereck (Jan 31, 2005)

robbob said:


> what are the advantages of clincher vs tubular - I was looking at picking up some Ksyriums on e-bay and have noticed the tubular costs much less... Whats the dif???
> 
> Thanks


Okay, this might not be fair, given the time gap.

But I once rode/raced almost exclusively on tubs. 700C happened when I was out of the sport for a while - 30 years!

Save you doing the sums - I last raced in 1973, didn't ride again seriously until 2004!

Even back then, I was one of few folk who could actually repair a tub. There's nothing to it, as long as you have the right stuff to do the job. Once one had been repaired, even if I repaired it myself, it was downgraded to training or time-trialing, depending on its weight unless economics forced it back onto my road race wheels ...

At that, I would never have contemplated the idea of a road-side tub repair  

Never recall any issues with sticking them onto rims, losing them while racing or even having to swap a tub post flat and the replacement not sticking after being fitted.

OTOH - seeing as things like really nice clincher tyres and modern wheels have been invented while I was out getting fat and idle, would only put up with the mess and fuss of tubs if I won the lottery and bought a set to cruise the neighbourhood on my $10,000 custom Ti weight-weenie poser bike  ! They're just too much trouble and fuss for whatever advantage an overweight 56 year old would gain over my present decent set of clinchers.

The viewpoint of a screaming fast 20-something Div 1 pro with 2% body fat and a three page palmares may be somewhat different 

Sometimes progress can actually be good  


Regards 

Dereck


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## MShaw (Jun 7, 2003)

Wow! Several posts and no religious argument.

What's the world coming to?!

Resale on tubulars sucks. DAMHIK 

If you go the tubie route, I'd seriously think about saving them for racing and train on clinchers. (at least that's what I do unless I'm on my cross bike)

M


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## newdoc (May 22, 2004)

there is a great tubular review elsewhere on this forum just search for it............


it seems to me, just like metal frame bikes are falling out of favor for carbon frames, i think the same process is happening with wheels.............however it is much more difficult to make a carbon clincher versus a carbon tubular.............this fact may just ressurect tubulars to more common use..............

a good light clincher weighs around 1600 grams, and a good light tubular weighs in the 1100-1200 gram range, roughly a pound lighter.........a significant improvement esp since it is rotating weight.........basically the only problem with tubulars is flat repair.........interestingly 2 companies that i know of make a tubular repair fix-flat type stuff , one is tufo and the other is vitorria.........if these really worked, then flat repair becomes easier than a clincher, which requires patching or replacing the tube.........


cost - good tubular tire and rims are expensive, but so are good carbon bikes... i ride a 4500$ carbon bike, so for me a 1600$ set of wheels is an option..........the next dillemma for me is which rim.......lighter shallow less aero rim or slightly heavier, stiffer but more aero........


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## psi_co (Sep 27, 2004)

I rode tubs on a test wheelset for a week and I didn´t get used to them.

I had no confidence while cornering, cause a rim with an edge will stick to the clincher, and the tubs felt like they´re really only sitting on top of the rim, and in the curves they felt very "round", while the clinchers always "bite" or cut themselves into the road, when you throw your bike into the corner.-maybe u get used to it and ir was just a phsycholgical thing, in my mind.

The weight-issue is an advantge with the tubulars, cause a 1k wheelset really makes you drive like having lost 3 kilos of bodyweight in a diet, but without dieting just mounting those wheels.


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## Mark McM (Jun 18, 2005)

newdoc said:


> a good light clincher weighs around 1600 grams, and a good light tubular weighs in the 1100-1200 gram range, roughly a pound lighter.........


That's a bit of an exageration. Tubular wheels and clincher wheels differ only in the rim (the the tires that are mounted). Tubular tires weigh about the same as equivalent clinchers and tubes. Tubular rims weight 50-100 grams less than equivalent clincher rims. That makes a total difference of about 100-200 grams for a set of wheels between tubulars and clinchers. The difference in rolling resistance between tubulars (higher) and clinchers (lower) generally cancel out even this weight difference. Everything else being equal, the lower weight of tubulars only becomes an advantage under very high accelerations or when climbing very, very steep slopes.




newdoc said:


> a significant improvement esp since it is rotating weight.........


Rotating mass only makes a difference when acceleration, not at steady state speeds (even when climbing). Due to the higher rolling resistance of tubulars, you'd have to be acceleration at a very high rate to make up for the higher rolling resistance.




newdoc said:


> basically the only problem with tubulars is flat repair.........interestingly 2 companies that i know of make a tubular repair fix-flat type stuff , one is tufo and the other is vitorria.........


Tire sealants can work to prevent flats in many cases. But they add additional weight, and increase rolling resistance.


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## peterpen (May 5, 2004)

two points -

aero - carbon tubs can be around 300gms @ 44mm deep - you can't get close to those #'s with a clincher.

and the placebo effect - knowing you have an 1200 gm wheelset has got to feel fast!


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## newdoc (May 22, 2004)

Mark McM said:


> That's a bit of an exageration. Tubular wheels and clincher wheels differ only in the rim (the the tires that are mounted). Tubular tires weigh about the same as equivalent clinchers and tubes. Tubular rims weight 50-100 grams less than equivalent clincher rims. That makes a total difference of about 100-200 grams for a set of wheels between tubulars and clinchers. The difference in rolling resistance between tubulars (higher) and clinchers (lower) generally cancel out even this weight difference. Everything else being equal, the lower weight of tubulars only becomes an advantage under very high accelerations or when climbing very, very steep slopes.
> 
> 
> _interesting thoughts_......._but if i ride durace 7801 clinchers and they weigh according to shimano specs about 1620 grams............and a rolf tdf38 weighs 1175 grams for the set.....the math says a difference of 445 grams..........therefore I don't understand what the exageration is ???_[/U_]........plus the carbon tubulars are 38 mm deep rather than 23mm deep, i.e. considerably more aero, and therefore faster on the flats....._
> ...




_for sure, the point i was trying to make is, it would be easy to repair a flat on the road with the instant repair goop, and still be able to get home or to the finish on a long ride/race or tour........_


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## ultimobici (Jul 16, 2005)

Mark McM said:


> For comparable strength and durability, tubular rims are lighter, but tires are really about the same weight. (Actually, tubular tires are heavier, but that's only because the weight includes the tube inside. Combined weight of tire and tube of kevlar bead clinchers are about the same as for tubulars.)


I ride <215g tubs which are not hyper light. Tufo do <160g tyres. Conti Supersonic 700 x 20's come in at 140 with the tube at 50g. Couple that with the heavier rim & tubs win on that front, hands down.



> On the minus side, tubulars have been demonstrated to generally have higher rolling resistance than clinchers (all else being equal).


If that's so, why do professional teams still use them. Asics were sponsored by Michelin who don't market tubs, but had special lookalike tubs made for the team! Why would they do that if the clinchers were more efficient & lighter?



> But on the other hand, clinchers have a larger total air pocket, since it extends into the rim.


Ride a pair of clinchers then ride a comprable set of tubs. You'll see the difference, tubs are plusher, especially at higher pressures.


> Some of the best bike handling riders I know ride clinchers exclusively.


Their bike handling has nothing to do with their wheel/tyre choice, I suspect their reasons for using clinchers are economic & hassle factor.


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## Mark McM (Jun 18, 2005)

ultimobici said:


> I ride <215g tubs which are not hyper light. Tufo do <160g tyres. Conti Supersonic 700 x 20's come in at 140 with the tube at 50g. Couple that with the heavier rim & tubs win on that front, hands down.


There are <215 tubulars, but these are hardly the norm. A quick check on the Weight Weenies site (Weight Weenies tire list) shows that all the <215 tubular tires are 20mm or narrower, and most are classified as TT or special use category. More typical tubulars found on racing bikes are in the 250-300 gram range. If you were to compare clincher tires and tubular tires of otherwise identical construction (for example, the Vittoria Corsa CX tubular and Vittoria Open Corsa CX clincher), you'd find that the tubulars and clinchers+tubes were nearly identical in weight.




ultimobici said:


> If that's so, why do professional teams still use them. Asics were sponsored by Michelin who don't market tubs, but had special lookalike tubs made for the team! Why would they do that if the clinchers were more efficient & lighter.


I can't answer why pro teams use them, other than to point out that traditions die hard even among professional mechanics. However, while tubular rims can be lighter, it has been demonstrated again and again that tubular tires have more rolling resistance. The higher rolling resistance of tubulars has been shown so many times under so many different independent tests, there can no longer be any doubt. Here is just one such test: Tire test 




ultimobici said:


> Their bike handling has nothing to do with their wheel/tyre choice ...


That's exactly the point - bike handling is not a consideration in deciding between clinchers and tubulars, since there is no evidence that tubulars are intrinsically better for handling.


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## FTF (Aug 5, 2003)

Mark McM said:


> Rotating mass only makes a difference when acceleration, not at steady state speeds (even when climbing). Due to the higher rolling resistance of tubulars, you'd have to be acceleration at a very high rate to make up for the higher rolling resistance.


You keep touting the higher rolling resistance of tubulars, but the difference between a good clincher, and a good tubular are almost nothing. I would say that the difference between, say, a pro2race tire, and the Veloflex carbon, is pretty miniscule.... .0042 vs. .0049. Of course if you compare a good clincher to a crappy tubular like tufo, then your spot on. 

*Tire * *CRR*
Deda Tre Giro d'Italia	0.0038 
Vittoria Open Corsa Evo CX	0.0039 
Michelin Pro 2 Race	0.0042 
Vittoria Diamante Pro Rain	0.0044 
Michelin Megamium 2	0.0047 
Pariba Revolution	0.0048 
_Veloflex Carbon (Tubular)	0.0049_ 
Michelin Carbon	0.0050 
_Gommitalia Route du Nord (Tubular) 0.0050_ 
Panaracer Stradius Pro	0.0051 
Schwalbe Stelvio Plus	0.0052 
_Gommitalia Platinum (Tubular)	0.0053_ 
_Vittoria Corsa Evo CX (Tubular)	0.0054_ 
Schwalbe Stelvio Evolution Front	0.0056 
Continental GP Force (rear specific)	0.0057 
Hutchinson Fusion	0.0057 
Schwalbe Stelvio Evolution Rear	0.0057 
_Vittoria Corsa Evo KS (Tubular)	0.0057_ 
Continental Ultra GatorSkin	0.0058 
Ritchey Pro Race Slick WCS	0.0058 
Schwalbe Stelvio	0.0059 
_Continental Competition (Tubular)	0.0059_ 
_Veloflex Roubaix (Tubular)	0.0059_ 
_Continental Podium (Tubular)	0.0060_ 
Specialized S-Works Mondo	0.0061 
Continental GP 3000	0.0067 
Hutchinson Top Speed	0.0069 
_Schwalbe Stelvio (Tubular)	0.0069_ 
Continental GP Attack (front specific)	0.0073 
_Tufo Elite Jet (Tubular)	0.0073_ 
_Schwalbe Montello 300 (Tubular)	0.0075_ 
_Tufo Hi-Composite Carbon (Tubular)	0.0077_ 

Average Clincher: 0.0054 
_Average Tubular: 0.0061_


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## ultimobici (Jul 16, 2005)

Mark McM said:


> There are <215 tubulars, but these are hardly the norm. A quick check on the Weight Weenies site (Weight Weenies tire list) shows that all the <215 tubular tires are 20mm or narrower, and most are classified as TT or special use category.


Tufo S3 Lite <215 g are 21mm Road Racing Tubs. They equate to Conti Supersonics or Deda Tre Tyres in that they are not for every day use.

http://www.tufo.com/index.php?lg=en&mn=1&id=53


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## newdoc (May 22, 2004)

thanks for the info on the tires..........I wonder at what air pressure those numbers were determined ??........prob very difficult to know, but would be interesting if the data were taken at matched air pressure of tubular versus clincher , or if it was measured at max pressure of either tire ??


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## FTF (Aug 5, 2003)

newdoc said:


> thanks for the info on the tires..........I wonder at what air pressure those numbers were determined ??........prob very difficult to know, but would be interesting if the data were taken at matched air pressure of tubular versus clincher , or if it was measured at max pressure of either tire ??


101 psi.


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## newdoc (May 22, 2004)

cool........then to take your point on step further clinchers ride comparably better and more supple and more comfortable..........so you could deduce that a tubular vs clincher at equal pressure, the tubular would ride alot more comfortably, which on a long taining ride or century would be very welcome...........and further if you went ahead and brought the tubular air pressure up to the max for the tire, which for many is way higher than that for a clincher, the rolling resistane should further improve, and likely improve considerably over the clinchers rolling resistance........


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## alienator (Jun 11, 2004)

robbob said:


> what are the advantages of clincher vs tubular - I was looking at picking up some Ksyriums on e-bay and have noticed the tubular costs much less... Whats the dif???
> 
> Thanks


The advantage of tubulars is that if you don't mind tubulars you, too, can own and use a set of Carbon Sport's Lightweight wheels.......wheelsets that are all 1000ish g, +/-100g or so. And they'll only cost you $3000-4000 or so. Now how much better can you get than that?


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## brewster (Jun 15, 2004)

Been there, done that.

If we were having this discussion in 1987, there would not be much discussion, tubies were superior in nearly every category. However, this is 2006, and clinchers have come a long, long way. With the quality and price of modern clinchers, I don't see one good reason to put up with all the hassles you will incur with tubies.

brewster


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## Mark McM (Jun 18, 2005)

*Almost nothing cancels almost nothing*



FTF said:


> You keep touting the higher rolling resistance of tubulars, but the difference between a good clincher, and a good tubular are almost nothing. I would say that the difference between, say, a pro2race tire, and the Veloflex carbon, is pretty miniscule.... .0042 vs. .0049. Of course if you compare a good clincher to a crappy tubular like tufo, then your spot on.
> 
> 
> Average Clincher: 0.0054
> _Average Tubular: 0.0061_


Yes, you're right, the differences between rolling resistance between tubulars and clinchers is very small. But the difference between the weights of tubulars and clinchers is also very small. Let's look at an example:

Say a 75 kg a rider who normally rides a 10 kg bike with average tubular tires (Crr = 0.0061). When riding at steady state speed, the rider has this much rolling resistances:

Frr = Crr x M x g = (0.0061) x (75+10 kg) x (9.81 m/s^2) = 5.09 N

When riding at 11 m/s (24.6 mph), the rolling resistance power losses are:

Prr = (5.09 N) x (11 m/s) = 56.0 Watts

This is roughly 20% of the total power.

Say the same rider switches to a bike with average clincher tires (Crr = 0.0054) and that weighs 10.5 kg (0.5kg more):

Frr = (0.0054) x (75 + 10.5 kg) x (9.81 m/s^2) = 4.53 N

Prr = (4.53 N) x (11 m/s) = 49.8 Watts

A savings of 6.2 W, or 11% of rolling resistance losses, or about 2% of total power. This is a significant difference, and is on par with the power savings of many aero wheels (except of course that the tires are cheaper than the wheels, and easier to repair).

Of course, the rider has to lug the extra weight of the clinchers up hill, which will act to cancel out the decrease in rolling resistance. But how steep does the grade have to be before the extra weight of the clinchers hurts more than the lower rolling resistance helps?

The required push a bike up hill against gravity is related to the mass and the slope of the road:

Fg = M x g x Sine( Slope ) 

We can find the slope where the two affects (extra weight and lower rolling resistance of clinchers) exactly cancel out by setting the sums of the rolling resistances and gravity forces of the two bikes equal:

Fg + Frr = M x g x Sine( Slope ) + Crr x M x g = (M x g)( Sine(Slope) + Crr )

(Fg + Frr)[tubulars] = (Fg + Frr)[clinchers]

{ (75 + 10 kg) x (9.81 m/s^2) }{ 0.0061 + Sine( Slope ) } = { (75 + 10.5 kg) x (9.81 m/s^2) }{ 0.0054 + Sine( Slope ) }

834 x Sine( Slope ) + 5.09 = 839 x Sine( Slope ) + 4.53

Slope = ArcSine( (5.09 - 4.53)/(839-834) = 0.112 ) = 6.43 deg. = 11.3%

Or in other words, the lower weight of tubulars only cancels out the lower rolling resistance of clinchers when climbing at grades of 11.3% or greater. At all other times there is greater savings from the lower rolling resistance of clinchers. Therefore, the vast majority of time, even on rolling or hilly courses, the clinchers will be an advantage.

How about when accelerating? The clincher tires reduce rolling resistance drag, leaving more power available for accelerating, but more mass needs to be accelerated. But which affect is more signficant? A sprinter might be able to produce an instantaneous maximum power about 3 to 4 times higher than their steady state power. So if the clincher tires can save about 2% of steady state power, they would only be able to save 0.5-0.7% of maximum sprint power. But the extra weight of the clincher wheels in this example (0.5 kg) is only 0.59% of the total weight (85 kg). The two affects (more available power to sprint, more mass to accelerate) just about cancel out, and there is no disadvantage to the clinchers. (Or course, when accelerating at less than maximum power, the clinchers still come out ahead.)

About the only two places the clinchers don't come out ahead are:

- When tires are glued with hard glues, as for track tires. Most of the additional rolling resistance losses with tubulars are due to the hysteresis losses in tacky soft glues used on road tires. Hard glues are not used on road tires because solvents are required to remove and replace tires, which is not practical for replacing tires on the road.

- Ultra-deep aero wheels. Ultra-deep aero rims are primarily made from carbon fiber, so they are almost exclusively made for tubulars. For very deep aero wheels, the aerodynamic power savings can cancel out the extra rolling resistance of the tubular tires. Moderately deep rims (such as the 30mm or less rims found on most road wheels) are usually made in both tubular and clincher configurations, so the clincher version will have the lowest total drag (even when climbing moderate grades - see above).


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## asgelle (Apr 21, 2003)

Mark McM said:


> Yes, you're right, the differences between rolling resistance between tubulars and clinchers is very small. But the difference between the weights of tubulars and clinchers is also very small. Let's look at an example: ...


Very nice.


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## newdoc (May 22, 2004)

that is a great analysis...........however, if I read it correctly your calculations were based on 2 troubling assumptions:

1. the the rolling resistance was actually worse on tubular tires, i agree the average is higher, but some tubulars were actually lower than the clinchers in rolling resistance and those numbers didn't account for a tubular at max air pressure......

2. the weight calculations were based on gross weight, and didn't account for rotational weight or inertia...........it has been approximated that weight saved in the wheels has an effect approximately 3 times that of just total bike and rider weight changes........

3. if carbon tubulars were such a bad idea then why do so many pros ride them ??


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## MShaw (Jun 7, 2003)

newdoc said:


> that is a great analysis...........however, if I read it correctly your calculations were based on 2 troubling assumptions:
> 
> 1. the the rolling resistance was actually worse on tubular tires, i agree the average is higher, but some tubulars were actually lower than the clinchers in rolling resistance and those numbers didn't account for a tubular at max air pressure......
> 
> ...


Forget it dude. Yer arguing with an engineer with his mind made up. BTDT with Jobst Brandt on numerous occaisions.

You ARE NOT going to get him to change his mind. Period. No matter what the _actual_ differences between clinchers and tubulars are, the shutters are closed. 

'Course I know that I LOVE the way my tubulars ride. I also know that modern clinchers are about as good, _but not quite._ I race on tubies and for the convenience, train on clinchers. Used to train on tubulars, but a few rides with 2+ flats _out there_ convinced me otherwise.

My $.02:
New good tubulars will outride new good clinchers by a small margin
New good clinchers are gonna outride new crappy tubulars by bigger margins.

M


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## FTF (Aug 5, 2003)

Mark McM said:


> Yes, you're right, the differences between rolling resistance between tubulars and clinchers is very small. But the difference between the weights of tubulars and clinchers is also very small. Let's look at an example:
> 
> Say a 75 kg a rider who normally rides a 10 kg bike with average tubular tires (Crr = 0.0061). When riding at steady state speed, the rider has this much rolling resistances:
> 
> ...


Yes, but to me the main advantage of tubulars, as I stated in my very first post, is the ability to ride them around the course, to get a wheel change. I'll sacrafice 6 watts for that ability. Why? Becuase I don't race in a lab. You'll notice I never said anything about weight.


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## FTF (Aug 5, 2003)

newdoc said:


> that is a great analysis...........however, if I read it correctly your calculations were based on 2 troubling assumptions:
> 
> 1. the the rolling resistance was actually worse on tubular tires, i agree the average is higher, but some tubulars were actually lower than the clinchers in rolling resistance and those numbers didn't account for a tubular at max air pressure......
> 
> ...


I'm going to come to MCM's defense abit here, becuase I agree with him, more or less. 

1. The point is you can get clinchers with a lower crr than tubies, not that all of them are. The clincher tires I use are Pro2 races, which as you'll see have a very low crr, lower than any tubie. But if your using the gp4000, your going to be on a tire that has more crr than most of the good tubies on that list. What does this mean to me in the end? The tires crr isn't going to be winning me any races. My point with the list was just that, the differences are so minor, that any good tire won't help or keep you from winning. The ability to keep riding on that last lap, though, that's something that will help, and yes I HAVE seen it happen. 

2. This really wouldn't change much of anything, again it wouldn't be enough to really help or hurt you.


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## FTF (Aug 5, 2003)

newdoc said:


> cool........then to take your point on step further clinchers ride comparably better and more supple and more comfortable..........so you could deduce that a tubular vs clincher at equal pressure, the tubular would ride alot more comfortably, which on a long taining ride or century would be very welcome...........and further if you went ahead and brought the tubular air pressure up to the max for the tire, which for many is way higher than that for a clincher, the rolling resistane should further improve, and likely improve considerably over the clinchers rolling resistance........


If you brought the pressure up to the max on the tire, you would raise the rolling resistance, becuase instead of rolling over the road, you would be bumping over it. Higher pressure _feels _faster, but isn't actually faster.


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## alienator (Jun 11, 2004)

newdoc said:


> that is a great analysis...........however, if I read it correctly your calculations were based on 2 troubling assumptions:
> 
> 1. the the rolling resistance was actually worse on tubular tires, i agree the average is higher, but some tubulars were actually lower than the clinchers in rolling resistance and those numbers didn't account for a tubular at max air pressure......
> 
> ...


1. As has been said here and elsewhere many times, high pressure does not equal lower rolling resistance. Optimal tire pressure is NOT the max pressure written on the side of the tire.

2. As Mark McM said, and as you'd find in any Newtonian mechanics text, the weight of the bike/rider system is what you have to do work to move. This weight also impacts frictional losses. Rotational weight doesn't matter so much as a given rotating parts moment of inertia. Then, the rider only does work when he wants to increase the angular momentum of said rotating parts. Braking is effected by the angular momentum, as is coasting, but bike rider's don't spin the cranks & wheels fast enough to make the difference in moment of inertia between wheels really noticeable.

As for the approximation, it's just that, and not a very accurate one at that. Even if the approx. was true, you replaced a wheelset with another set that weighed 200g less (0.44lbs), and you together with your bike weighed 160 lbs before the wheel change, the total actual weight change would be 0.275%. If you then used the "3x" approx, then the claim would be that you'd have an apparent weight loss of 0.825%. That's miniscule. Granted over a long day, you'd be likely to realize some energy savings, but it's not something you'd notice anytime you jumped up to stomp on the pedals.

3. Why a pro rides something is a matter of sponsorship, mythology, and hair splitting. For the pro, a 0.275% difference in weight might translate to winning by a nose after a long day, maybe by less than a nose.

I'd like to have a set of Lightweight Obermayers. They're 1050g, and that's an easy, albeit expensive way to lose roughly 400g off the bike. But I'm under no illusion that they'd turn me into the second coming of Eddie M. I'd like to make my bike as light as is feasible but only as an exercise to that end. It's a gearhead thing.


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## newdoc (May 22, 2004)

hmmmmmmmmmmm.........you guys are making some good points.............


just one more thing.......the conti gp3000 are .0066 on rolling resistance and the gp4000 are reported as .0053 , which is acutally pretty good............i went from conti 4 season to the gp4000 and it sure feels like they roll better...........

maybe you guys have saved me about 2 grand..........it sure makes it harder to justify that much cash for such a small improvement...........


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## jroden (Jun 15, 2004)

The tubular is nice because you can grind along on the flat tire for a long time at a decent speed while waiting for a support vehicle to get close, for example, you could get up a hill when the pack is strung out and have some chance of re joining the race. I would not buy wheels based on this feature alone, but it is nice when you need it.


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## Mark McM (Jun 18, 2005)

*Flat clinchers*



FTF said:


> Yes, but to me the main advantage of tubulars, as I stated in my very first post, is the ability to ride them around the course, to get a wheel change. I'll sacrafice 6 watts for that ability. Why? Becuase I don't race in a lab. You'll notice I never said anything about weight.


I've had no problem riding a flatted clincher (either front and back) around a crit course to the wheel pit, with plenty of time to get a wheel change and get back into the race.

Contrary to popular myth, you can ride a flat clincher without falling down.


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## Mark McM (Jun 18, 2005)

*Assumptions and advantages*



newdoc said:


> that is a great analysis...........however, if I read it correctly your calculations were based on 2 troubling assumptions:
> 
> 1. the the rolling resistance was actually worse on tubular tires, i agree the average is higher, but some tubulars were actually lower than the clinchers in rolling resistance and those numbers didn't account for a tubular at max air pressure......


Yes, some tubulars do have better rolling resistance than some clinchers. But if you were selecting tires based on rolling resistance, you'd select a clincher that has lower rolling resistance than all the tubulars. 

Even though tubulars often have higher pressure limits, that doesn't mean that they can acheive lower rolling resistance than a lower pressure clincher. The relationship between rolling resistance and pressure is asymptotic - there is an upper limit, and extra pressure won't lower it further. Here are some data a graphs comparing the rolling resistance of a variety of clinchers and tubulars over a range of pressures: Rolling resistance graphs. As you can see, the graph of tubular rolling resistance tends to flatten out at higher presssures (little change with increasing pressure), and never gets as low as the better clincher tires. On the graph, the best tubular, the Clement Seta 250 (a silk casing tubular) has the same rolling resistance at 9 bars (132 psi) as the Avocet Criterium (a 23mm clincher) at 6 bars (85 psi).



newdoc said:


> 2. the weight calculations were based on gross weight, and didn't account for rotational weight or inertia...........it has been approximated that weight saved in the wheels has an effect approximately 3 times that of just total bike and rider weight changes........


It seems like every time this is repeated, the number gets bigger. I've heard people claim rotating weight is worth 2 times as much, 3 times as much 4 times as much, and even 10 times as much as non-rotating weight.

The real answer is that rotating mass _at the periphery of the wheel_ has twice the inertia as the same amount of non-rotating mass (rotating between the center and the perimeter of the wheel has been 1 and 2 times the inertia, depending on the radius).

But inertia only affects acceleration. Rotating mass has no more or less affect than non-rotating mass when riding at a steady speed. Even when climbing, it makes no difference if the mass is rotating or not.

It should also be noted that the lower weight of tubular wheels can only be taken advantage by riders with support vehicles following them. Most riders don't have support vehicles, so they must carry spare tires with them. A set of tubular wheels plus a spare tire weighs more than a set of clincher wheels plus a spare tube.



newdoc said:


> 3. if carbon tubulars were such a bad idea then why do so many pros ride them ??


Well, they're not necessarily a very bad idea, they're just not as good an idea as many seem to think. As I said before, you'd have to ask the pros themselves why they ride tubulars. Many, if not most, pro team equipment decisions are based on sponsor commitments, so this may play a role in tire selection. It should also be noted that most riders and mechanics are not scientists or engineers, and are no less immune to traditional and folklore than anyone else. At the same time, you might want to ask why almost all tubular tires (including those used by pro teams) have patterned tread, when patterned tread is not only unnecessary on bicycle tires, but both increases rolling resistance and decreases traction.

The choice of tubulars by pro tems could be because of some other differences between tubulars in clinchers not directly related to performance, like that tubulars are a bit less prone to pinch flatting (although not totally immune - I've seen tubulars pinch flatted on several occasions). But, as noted above, you need to be followed by a vehicle with spare wheels (as the pros are) to reap all the potential advantages of tubulars.


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## Mark McM (Jun 18, 2005)

*Minds, open and closed*



MShaw said:


> Forget it dude. Yer arguing with an engineer with his mind made up. BTDT with Jobst Brandt on numerous occaisions.
> 
> You ARE NOT going to get him to change his mind. Period. No matter what the _actual_ differences between clinchers and tubulars are, the shutters are closed.


Nice ad hominem attack. I guess if you can't shoot the message, shoot the messenger instead.

Even still, you have it exactly wrong. My mind is completely open - but it is open to facts and data. The facts and data currently show that there is little or no advantage to tubulars, and in fact many disadvantages. If you can demonstrate that there are advantages to tubulars, please do so, and I'll listen. Unless and until you can do that, it appears as though it is your mind that is closed, not mine.


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## FTF (Aug 5, 2003)

Mark McM said:


> I've had no problem riding a flatted clincher (either front and back) around a crit course to the wheel pit, with plenty of time to get a wheel change and get back into the race.
> 
> Contrary to popular myth, you can ride a flat clincher without falling down.


Yes, but not at the same speed, what about if you were in the last lap etc?


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## FTF (Aug 5, 2003)

Mark McM said:


> Many, if not most, pro team equipment decisions are based on sponsor commitments, so this may play a role in tire selection.


I highly doubt this is it, considering how popular Clinchers are, compared to how rare tubulars are, it would make no sence to spend your marketing dollars on tubular tires.


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## MShaw (Jun 7, 2003)

Mark McM said:


> Nice ad hominem attack. I guess if you can't shoot the message, shoot the messenger instead.
> 
> Even still, you have it exactly wrong. My mind is completely open - but it is open to facts and data. The facts and data currently show that there is little or no advantage to tubulars, and in fact many disadvantages. If you can demonstrate that there are advantages to tubulars, please do so, and I'll listen. Unless and until you can do that, it appears as though it is your mind that is closed, not mine.


Ummm, dude. There's more to life than data sets. Describe in an equation 'feel.'

That right there is where experience (almost 20 years in my case) and numbers disagree.

Now, who has an open mind again? Hmmmm?

M


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## alienator (Jun 11, 2004)

MShaw said:


> Ummm, dude. There's more to life than data sets. Describe in an equation 'feel.'
> 
> That right there is where experience (almost 20 years in my case) and numbers disagree.
> 
> ...


I'm not quite sure how your interpretation of "feel" is applicable to other people.......I guess that's because it isn't. Mark McM only showed that there was no empirical evidence to support the idea that tubulars were superior. Feel is wholly personal....just like choosing a saddle. Just because my tushy likes my Arione saddle doesn't mean that it will have better "feel" for everyone else.


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## olddog (Dec 5, 2004)

Mark McM said:


> Rotating mass only makes a difference when acceleration, not at steady state speeds (even when climbing). Due to the higher rolling resistance of tubulars, you'd have to be acceleration at a very high rate to make up for the higher rolling resistance.


Mark (and other engineer types), I've recently become aware of the claim that rotating weight is really no different than any other weight, and of course this contradicts what I've "known" for 30+ years of cycling. My one question on this whole issue is: isn't climbing a constant state of acceleration? For instance, when in my "underpowered" Honda CRV (still more power than I have I'm guessing) I have to pretty much floor it to maintain my speed up big hills - even then it's mostly a losing battle as the car slowly (or rapidly depending on the hill/mountain) loses speed. For small hills I can understand that this has little overall effect, but I live at the base of a rather large hill called the Beartooth Pass (my favorite ride) which is 32 miles to the top at a rather constant 6 - 7 percent grade with 5,500' of elevation gain, topping out just shy of 11,000 ft. It takes me about 3 hours to get to the top - the best time I'm aware of is 2 hours 15 minutes. In this instance might rotating weight actually make a noticable difference? Even if the amount of energy required to accelerate a ligher wheel is very small, when totaled over this large a distance might it have a substantial cumulative effect?

Thanks,
John W.


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## Kerry Irons (Feb 25, 2002)

*Simple physics*



olddog said:


> I've recently become aware of the claim that rotating weight is really no different than any other weight, and of course this contradicts what I've "known" for 30+ years of cycling. My one question on this whole issue is: isn't climbing a constant state of acceleration? In this instance might rotating weight actually make a noticable difference? Even if the amount of energy required to accelerate a ligher wheel is very small, when totaled over this large a distance might it have a substantial cumulative effect?


In a word, no. Once the wheel has been spun up to speed, you have stored the rotational kinetic energy - no more is required to maintain speed. If your speed is surging with each pedal stroke, it takes less energy to speed up the lighter wheel, but you get less energy back when your speed drops. When climbing a hill, it is functionally the total weight that matters, and whether the weight is in your water bottle or your rim and tire makes no difference. The only situation where rotational vs. "regular" weight makes a difference is when you change speed and stay at the different speed. This is only the case when you are sprinting (and there aero makes more difference) or jumping out of corners in a crit, and then braking to "throw away" the rotational energy.

BTW, this is not a "claim," it is simple physics.


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## MShaw (Jun 7, 2003)

alienator said:


> I'm not quite sure how your interpretation of "feel" is applicable to other people.......


Surely, feel is part of what drives people to go ride tubulars. If that's the case, certainly someone has to have an equation to 'prove it.' Right? It goes back to my assertion that #s aren't everything when picking riding equipment. 



> Mark McM only showed that there was no empirical evidence to support the idea that tubulars were superior. Feel is wholly personal....just like choosing a saddle. Just because my tushy likes my Arione saddle doesn't mean that it will have better "feel" for everyone else.


Now you're talking about anatomical differences. Apples and oranges.

M


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## den bakker (Nov 13, 2004)

MShaw said:


> Surely, feel is part of what drives people to go ride tubulars. If that's the case, certainly someone has to have an equation to 'prove it.' Right? It goes back to my assertion that #s aren't everything when picking riding equipment.
> 
> 
> Now you're talking about anatomical differences. Apples and oranges.
> ...


Is that "feel" as in too hard pumped tires "feel" faster?


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## olddog (Dec 5, 2004)

Thanks Kerry. I remember seeing a chart a few years ago about the - for lack of a better term - effective weight differece in components of a wheel. I believe the hub was given a value of .97 (ie. effectively the same as any other weight on the bike), but as you moved away from the hub the value decreased (ie. giving the weight of the tire more "weight" if you will). I was under the impression at the time that these figures were the result of labratory testing. Was this simply the product of someone's imagination? I also remember similar statements about truck wheels/tires during my younger and foolish four wheeling days, and the main selling point for lighter aluminum rims. Also, your statement that "The only situation where rotational vs. "regular" weight makes a difference is when you change speed and stay at the different speed" is what I was trying to get at before. When your climbing don't you need to be in a state of continual acceleration in order to maintain your speed? To aviod losing the battle with gravity? To again use the car analogy; if I keep the accelerator at the same spot on a hill, my car will lose speed until I reach the top. In order to maintain my speed (or lose as little speed as possible, depending on hill size) I need to depress the gas pedal. Lets assume that my car is powerful enough to speed up. If I then return the gas pedal to the original position, the car will not maintain that speed, it will immediately begin losing speed again. Since I live in the mountains of Montana this is a very noticable and frequent occurence. So my point is, don't you need to be in a constant state of acceleration in order to maintain your speed while climbing? I know my car does. I realize that the main force I need to overcome is gravitys effect on the entire car, and not the weight of my car's wheels, but if the weight of the wheels does come into play "only" while accelerating, aren't I in a sense accelerating for 32 miles when I climb the pass? Please enlighten me on this - old minds are hard to change!



Kerry Irons said:


> In a word, no. Once the wheel has been spun up to speed, you have stored the rotational kinetic energy - no more is required to maintain speed. If your speed is surging with each pedal stroke, it takes less energy to speed up the lighter wheel, but you get less energy back when your speed drops. When climbing a hill, it is functionally the total weight that matters, and whether the weight is in your water bottle or your rim and tire makes no difference. The only situation where rotational vs. "regular" weight makes a difference is when you change speed and stay at the different speed. This is only the case when you are sprinting (and there aero makes more difference) or jumping out of corners in a crit, and then braking to "throw away" the rotational energy.
> 
> BTW, this is not a "claim," it is simple physics.


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## Kerry Irons (Feb 25, 2002)

*Confusion reigns*



olddog said:


> When your climbing don't you need to be in a state of continual acceleration in order to maintain your speed? To aviod losing the battle with gravity?


Acceleration is to go faster. Continual acceleration would mean that you are going faster, and faster, and faster as you climb. Your car analogy is totally inappropriate - if you are maintaining speed you are NOT accelerating, regardless of how much power you are putting out. The position of the accelerator in a car determines how much power is produced by the engine. If you hold the pedal steady, the engine will put out a constant amount of power, and your speed will remain constant - it's the same if you're pedaling at a constant power output. If your car is slowing down, that just means that it has not reached the equilibrium between speed and power output, but it will soon. 

The chart you saw that "weighted the weight" depending on where it was relative to the hub is simply trying to show the impact of rotational kinetic energy. However, and I repeat, this is only meaningful if your speed is changing. Surging speed just means that you spin up the flywheel (that is your rim/tire/tube) and store the energy. When you slow down, you get the energy back. 

Simple physics.


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## Kerry Irons (Feb 25, 2002)

*Can you feel it?*



MShaw said:


> Surely, feel is part of what drives people to go ride tubulars. If that's the case, certainly someone has to have an equation to 'prove it.' Right? It goes back to my assertion that #s aren't everything when picking riding equipment.


It's probably time to quote Erik Zabel on clinchers vs. tubualrs: "I can't feel any difference." But, what would he know?


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## olddog (Dec 5, 2004)

They say that a little knowledge is a dangerous thing, and when it comes to physics I'm a very dangerous man - a total of 2 semesters more years ago than I would like to admit. Through the haze though I do remember learning that "acceleration" technically is any change of speed or direction - am I remembering that incorrectly? So I guess that what my mind still can't quite grasp is the fact that say I'm pedaling along at 16 mph on a flat, as the road starts to rise if I maintain the same effort, I will lose speed. I therefore have to increase my power output to maintain the same speed, which to my mind (or more accurately, my body) is identical to accelerating on a flat. If the road gets steep enough, I'm putting out an all-out sprint effort just to maintain a steady (and embarassingly slow) speed. And if wheel weight truly had no additional impact on climbing speed or effort, wouldn't the pros use slightly heavier aero wheels on mountain stages to gain the benefits of aerodynamics on the way back down? I don't mean to be a PITA, just trying to understand.

Thanks again!



Kerry Irons said:


> Acceleration is to go faster. Continual acceleration would mean that you are going faster, and faster, and faster as you climb. Your car analogy is totally inappropriate - if you are maintaining speed you are NOT accelerating, regardless of how much power you are putting out. The position of the accelerator in a car determines how much power is produced by the engine. If you hold the pedal steady, the engine will put out a constant amount of power, and your speed will remain constant - it's the same if you're pedaling at a constant power output. If your car is slowing down, that just means that it has not reached the equilibrium between speed and power output, but it will soon.
> 
> The chart you saw that "weighted the weight" depending on where it was relative to the hub is simply trying to show the impact of rotational kinetic energy. However, and I repeat, this is only meaningful if your speed is changing. Surging speed just means that you spin up the flywheel (that is your rim/tire/tube) and store the energy. When you slow down, you get the energy back.
> 
> Simple physics.


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## Anti-gravity (Jul 16, 2004)

olddog said:


> They say that a little knowledge is a dangerous thing, and when it comes to physics I'm a very dangerous man - a total of 2 semesters more years ago than I would like to admit. Through the haze though I do remember learning that "acceleration" technically is any change of speed or direction - am I remembering that incorrectly? So I guess that what my mind still can't quite grasp is the fact that say I'm pedaling along at 16 mph on a flat, as the road starts to rise if I maintain the same effort, I will lose speed. I therefore have to increase my power output to maintain the same speed, which to my mind (or more accurately, my body) is identical to accelerating on a flat. If the road gets steep enough, I'm putting out an all-out sprint effort just to maintain a steady (and embarassingly slow) speed. And if wheel weight truly had no additional impact on climbing speed or effort, wouldn't the pros use slightly heavier aero wheels on mountain stages to gain the benefits of aerodynamics on the way back down? I don't mean to be a PITA, just trying to understand.
> 
> Thanks again!


You have a couple different situation going on here.

First off on flat ground, the main source of resistance (a force directed in the opposite direction) is from the air you are displacing as you move through it. At average bicycle speeds, the force of air resistance is approximately proportional to the velocity of the bicycle squared (and the your power output to the third power). This is what prevents a bicycle (or any vehicle) from accelerating indefinitely while putting out a constant amount of power (and a steady force). Reverting back to Newton's Second law (F=ma) shows that a force causes an acceleration proportional to the mass. When you have stopped accelerating under a steady power output, the force of air resistance has built up (remember ~v^2) so that it is the same magnitude and opposite direction as the force you apply forward. So you stay at a constant velocity. This is the same reason why a sky diver free falling eventually reaches a terminal velocity instead of continually accelerating under the force of gravity.

When you start to climb, things change a little. You are gaining altitude and a component of your forward motion is also going up, fighting against the force of gravity. Like with wind resistance, the forces of you propelling the bike and gravity balance out under a constant power output and you remain at a constant velocity. You are also raising your gravitational potential energy (mass x acc. of gravity x altitude gained) which requires work on your part equal to amount of potential energy you gain (not including working against air resistance). Wind resistance becomes less of a factor because of the lower speeds, but is still contributing to opposing your acceleration. I know in some low velocity realm, the force of air resistance becomes more linearly proportional to the velocity, but I'm not sure if that every happens with a bicycle. That's engineering, which isn't my cup of tea.


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## den bakker (Nov 13, 2004)

yes acceleration is change of velcity, for this purpose lets just concentrate on the speed part. 
you pedal on the flat and hit the hill. To maintain the speed you increase your power. Your speed is maintained, i.e. not changing, you have already answered the question. If you had been on a flat you would have accelerated. But you are not so that is irrelevant. The rotational energy in the wheels has not changed despite your change in power output. 

Descending steep mountains is a lot of turning and braking, not sure that is fun with a set of deep aero wheels. On technical courses, some people use less aero wheels for better control (LA in this years tour is the obvious example, Michael Rasmussen is the example what happens with a disk wheel and bad preparation). 



olddog said:


> They say that a little knowledge is a dangerous thing, and when it comes to physics I'm a very dangerous man - a total of 2 semesters more years ago than I would like to admit. Through the haze though I do remember learning that "acceleration" technically is any change of speed or direction - am I remembering that incorrectly? So I guess that what my mind still can't quite grasp is the fact that say I'm pedaling along at 16 mph on a flat, as the road starts to rise if I maintain the same effort, I will lose speed. I therefore have to increase my power output to maintain the same speed, which to my mind (or more accurately, my body) is identical to accelerating on a flat. If the road gets steep enough, I'm putting out an all-out sprint effort just to maintain a steady (and embarassingly slow) speed. And if wheel weight truly had no additional impact on climbing speed or effort, wouldn't the pros use slightly heavier aero wheels on mountain stages to gain the benefits of aerodynamics on the way back down? I don't mean to be a PITA, just trying to understand.
> 
> Thanks again!


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## alienator (Jun 11, 2004)

olddog said:


> They say that a little knowledge is a dangerous thing, and when it comes to physics I'm a very dangerous man - a total of 2 semesters more years ago than I would like to admit. Through the haze though I do remember learning that "acceleration" technically is any change of speed or direction - am I remembering that incorrectly? So I guess that what my mind still can't quite grasp is the fact that say I'm pedaling along at 16 mph on a flat, as the road starts to rise if I maintain the same effort, I will lose speed. I therefore have to increase my power output to maintain the same speed, which to my mind (or more accurately, my body) is identical to accelerating on a flat. If the road gets steep enough, I'm putting out an all-out sprint effort just to maintain a steady (and embarassingly slow) speed. And if wheel weight truly had no additional impact on climbing speed or effort, wouldn't the pros use slightly heavier aero wheels on mountain stages to gain the benefits of aerodynamics on the way back down? I don't mean to be a PITA, just trying to understand.
> 
> Thanks again!


The problem you're having is that you're not stating the problem correctly. In addition to constraining the problem according to speed, you also need to constrain it according to energy. Climbing requires increasing the potential energy of the bike/rider system w/ respect to gravity. To maintain the constant speed you'd like to maintain, as you the grade changes you need to increase power output, since with each incremental displacement forward, the potential energy of the system is increasing more quickly (again, this is positional potential energy). In other words, as the road steepens, for every meter you move forward, you need to raise the bike/rider system higher. Since you're raising the bike higher, you need to do more work. Since you want to maintain the same speed, that means you have to do more work in the same interval of time, i.e. increase power. For this simple model, there is not acceleration.


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## olddog (Dec 5, 2004)

Thanks guys, by golly I think I at least partially understand now. Thanks for taking the time to explain it, in simple terms, to this simpleton.

John W.



alienator said:


> The problem you're having is that you're not stating the problem correctly. In addition to constraining the problem according to speed, you also need to constrain it according to energy. Climbing requires increasing the potential energy of the bike/rider system w/ respect to gravity. To maintain the constant speed you'd like to maintain, as you the grade changes you need to increase power output, since with each incremental displacement forward, the potential energy of the system is increasing more quickly (again, this is positional potential energy). In other words, as the road steepens, for every meter you move forward, you need to raise the bike/rider system higher. Since you're raising the bike higher, you need to do more work. Since you want to maintain the same speed, that means you have to do more work in the same interval of time, i.e. increase power. For this simple model, there is not acceleration.


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## weiwentg (Feb 3, 2004)

Mark McM said:


> Here is just one such test: Tire test


Mark, I'm very glad you threw some gasoline on the fire by posting that link. the test confirms two subjective assessments I made: that my GP3ks were a little slower than my beloved Pro Races, and that Tufos were complete and utter crap. people have been denying that Tufos roll like tofu for a long time, but now we know. I must say, though, I was pretty surprised that the differences between the top tubies and the top clinchers were that great - and in favor of the clinchers. now what do I do with my tubulars wheels?


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## salvadorvela (Jan 18, 2005)

*Make money on the Bike? or Spend Money on the Bike?*

Robbos, I don´t know much about Stat´s, but I love ridong My Bike in Competition Locvaly (Do mit for Fun and Excercise), I would Say, If you compete on a team, and make money, or you don´t care about money, get the Tubulars, that´s what the Pro Use for a reason (Don´t exactly know which), but if your a regular Weekend competition guy like myself, get the Clinchers, as I do. I´ve heard tubulars require a better and more profesional maintenance. But that´s what I´ve Heard. If you note that there cheaper, that´s the reason. And Friends say that they do "FEEL" better, not that it makes them a better racer.


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## homebrew (Oct 28, 2004)

alienator said:


> 1. As has been said here and elsewhere many times, high pressure does not equal lower rolling resistance. Optimal tire pressure is NOT the max pressure written on the side of the tire.
> 
> 2. As Mark McM said, and as you'd find in any Newtonian mechanics text, the weight of the bike/rider system is what you have to do work to move. This weight also impacts frictional losses. Rotational weight doesn't matter so much as a given rotating parts moment of inertia. Then, the rider only does work when he wants to increase the angular momentum of said rotating parts. Braking is effected by the angular momentum, as is coasting, but bike rider's don't spin the cranks & wheels fast enough to make the difference in moment of inertia between wheels really noticeable.
> 
> ...


I just went from using Kysrium sl's to Campy Bora's. Whatever the lab boys say these wheel rock. No I have not become Eddy M. however I am climbing a bit faster and find I can jump on hills that on the K's I was just able to hold on but mostly my top end has improved due to the areo factor. I guess I'm able to sustain 2 to 5 KMPH faster depending on conditions. The wheels are stiffer then my K's as well. Not a hint of brake rub when out of the saddle on the hard climbs. In my opionion they handle better but this may just be due to being tubular. I still like my K's and will still use them for crits (hate crashing) but light areo wheels are a plus for anyone concerned about speed. Ask Jan why he spent his own money to buy LW's. He had free wheels and still chose to part with 3 to 5 grand.


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## Kerry Irons (Feb 25, 2002)

*Amazing!*



homebrew said:


> I guess I'm able to sustain 2 to 5 KMPH faster depending on conditions.


Boras are great wheels, and no one can argue with that. However, repeated studies have shown that, at 40 kph, the BEST aero wheels (like the Boras) will give you 0.65 kmph. You claim to be getting anywhere from 3 to 8 times more than that. At 48 kmph, this is a 1 kmph improvement in speed. 

In science, this is what is called the placebo effect, aka "the magic feather" (see Disney's Dumbo), or simple self-delusion. Time for you to collect some hard data, like repeated time trials on a known course with different wheels and in different conditions. I expect that you will quickly disabuse yourself of these notions of speed increases due to your Boras. Great wheels, but no magic feather.


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## Anti-gravity (Jul 16, 2004)

*Moreon*



Kerry Irons said:


> Boras are great wheels, and no one can argue with that. However, repeated studies have shown that, at 40 kph, the BEST aero wheels (like the Boras) will give you 0.65 kmph. You claim to be getting anywhere from 3 to 8 times more than that. At 48 kmph, this is a 1 kmph improvement in speed.
> 
> In science, this is what is called the placebo effect, aka "the magic feather" (see Disney's Dumbo), or simple self-delusion. Time for you to collect some hard data, like repeated time trials on a known course with different wheels and in different conditions. I expect that you will quickly disabuse yourself of these notions of speed increases due to your Boras. Great wheels, but no magic feather.


You didn't solve the feel equation to get that result, did you? If it feels faster, then how can the science you quote be true? In the higher velocity realm that bicycles travel, Newtonian mechanics break down and the theory of feel must be used to measure differences in bicycle speed. QED.

-R


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## FTF (Aug 5, 2003)

Kerry Irons said:


> Boras are great wheels, and no one can argue with that. However, repeated studies have shown that, at 40 kph, the BEST aero wheels (like the Boras) will give you 0.65 kmph. You claim to be getting anywhere from 3 to 8 times more than that. At 48 kmph, this is a 1 kmph improvement in speed.
> 
> In science, this is what is called the placebo effect, aka "the magic feather" (see Disney's Dumbo), or simple self-delusion. Time for you to collect some hard data, like repeated time trials on a known course with different wheels and in different conditions. I expect that you will quickly disabuse yourself of these notions of speed increases due to your Boras. Great wheels, but no magic feather.


Well, I for one subcribe to the idea that placebo effect is important. I know/knew a very very very good olympic rifle shooter, out shot Bob Foth on more than one occasion, very good, one time I was with him at nationals, and he saw some sighting thing, I dono what the heck it was, and his coach thought it was useless, some 25 dollar dodad, anyways, you could tell that he thought he needed it, and so he bought it, and the first match that he used it, he shot a personal best, he thought that thing was the "magic feather" as you put it. Was it the dodad? I doubt it, I'm sure it was all in his head, which is just as important as any real world gain that it could have given him. Anyways, you can't discount placebo effect in real world performance, imho. It's just a story, a true one, but none the less.


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## psi_co (Sep 27, 2004)

Kerry Irons said:


> Boras are great wheels, and no one can argue with that. However, repeated studies have shown that, at 40 kph, the BEST aero wheels (like the Boras) will give you 0.65 kmph. You claim to be getting anywhere from 3 to 8 times more than that. At 48 kmph, this is a 1 kmph improvement in speed.
> 
> In science, this is what is called the placebo effect, aka "the magic feather" (see Disney's Dumbo), or simple self-delusion. Time for you to collect some hard data, like repeated time trials on a known course with different wheels and in different conditions. I expect that you will quickly disabuse yourself of these notions of speed increases due to your Boras. Great wheels, but no magic feather.


You don´´t win today with a 36 roundspokes wheel, over a Zipp 303 or even a Cosmic elite wheelset.

A 350$ Comsic set will get your breakaway to the finsh-line a 36 spokes wheel won´t even get you making breakaway.


At let´s say 47Km/h it´s 100-200Watts more effort for sure, not 20-80Watts difference between a Rolf or Bontranger wheel, to a Lightweight, and even these minor windcutting effects, _could_ make the difference.


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## llvllatt (Jul 23, 2005)

psi_co said:


> You don´´t win today with a 36 roundspokes wheel, over a Zipp 303 or even a Cosmic elite wheelset.
> 
> A 350$ Comsic set will get your breakaway to the finsh-line a 36 spokes wheel won´t even get you making breakaway.
> 
> ...


 Fulcrum's Racing 1 wheels (quite similar to Ksyrium SL's) got a couple stage wins at the Giro this past year.

The pro's choice on wheels usually has nothing to do with what they think is faster or what they would prefer.. it's all about sponsorship and money. Wheel manufacturing companies are trying to make everyone think that carbon tubular wheels are the best for everything (I'm not saying they are, that's just what marketing is pushing us to think) becuase they're expensive and they can make a fortune off of them.

I might get a race wheelset this season (been racing on Campy Protons all of last season) but undecided between clinchers or tubulars... probably will get clinchers though (due to money.. or moreso lack of)


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## Anti-gravity (Jul 16, 2004)

*Yeah, I can agree with that.*



FTF said:


> Well, I for one subcribe to the idea that placebo effect is important. I know/knew a very very very good olympic rifle shooter, out shot Bob Foth on more than one occasion, very good, one time I was with him at nationals, and he saw some sighting thing, I dono what the heck it was, and his coach thought it was useless, some 25 dollar dodad, anyways, you could tell that he thought he needed it, and so he bought it, and the first match that he used it, he shot a personal best, he thought that thing was the "magic feather" as you put it. Was it the dodad? I doubt it, I'm sure it was all in his head, which is just as important as any real world gain that it could have given him. Anyways, you can't discount placebo effect in real world performance, imho. It's just a story, a true one, but none the less.


Racing for me is so psychological, that having something on my bike that makes me feel fast could easily get me excited and energized and thus put out more power and effort. Also consider the fact that being a full-time student with a part-time job makes it difficult for me to train to my absolute potential, so I have more room to improve my performance through increased training (quit job, take less classes) then by pimping the ride. At my skill level, I just can't justify (IMO) getting a $3000 wheelset. I'd probably feel embarrassed going so slow on such a nice set of wheels that are better deserved under the legs of a Cat 1/ Pro racer. 

The data sheets aren't everything, but they do give more consistent quantitative information that someone's opinion or "feeling" ever will. If someone who is at the top of their fitness level is counting each second for their next TT, then looking at experimental data would probably give the best information. If you're a rec rider or racer not concerned with mathematics, then all things qualitative such as "stiffness", vibration damping, perceived speed increase or "comfort" may be the answers to your questions. If you drop $4k on something and you like what it does, real or imagined, then I think you got your money's worth.


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## FTF (Aug 5, 2003)

Anti-gravity said:


> Racing for me is so psychological, that having something on my bike that makes me feel fast could easily get me excited and energized and thus put out more power and effort. Also consider the fact that being a full-time student with a part-time job makes it difficult for me to train to my absolute potential, so I have more room to improve my performance through increased training (quit job, take less classes) then by pimping the ride. At my skill level, I just can't justify (IMO) getting a $3000 wheelset. I'd probably feel embarrassed going so slow on such a nice set of wheels that are better deserved under the legs of a Cat 1/ Pro racer.
> 
> The data sheets aren't everything, but they do give more consistent quantitative information that someone's opinion or "feeling" ever will. If someone who is at the top of their fitness level is counting each second for their next TT, then looking at experimental data would probably give the best information. If you're a rec rider or racer not concerned with mathematics, then all things qualitative such as "stiffness", vibration damping, perceived speed increase or "comfort" may be the answers to your questions. If you drop $4k on something and you like what it does, real or imagined, then I think you got your money's worth.


Yes, I'm with you, and I also think that training allot also has a psychological effect, as well as a physical one. Also, I'm not just talking about 3K wheels, and all of that, for some it might be finding the tire with the least rolling resistance, or the bar that allows them to get to the perfect position, hell even the right bartape. And don't get me wrong, I think it's pretty obvious that our shooter here trained allot, infact I know he did, allot. 

This is my thinking on the matter, dodads and fancy wheels won't change allot for the poorly trained athlete, but they might make the tiny mental difference in the trained athlete. The fastest wheels in the world are never a substute for training. I race on box rimmed wheels, but I have a "special" set that's lighter for racing, are those few extra grams going to make me faster, well I think that they do, and I like to keep myself thinking that, so keep your data sheets to yourself. My wheels cost me right around 500 dollars, they are custom wheels, not factory things. 

So, if I want to train my ass off for 20 hours a week, and then throw on some magic 500 dollar wheels, who's to fault me, that's what works for me. If someother guy beats me, and he's rolling on 3k wheels, I feel no ill will towards him, becuase my wheels are just as effective as his.


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## alienator (Jun 11, 2004)

Anti-gravity said:


> You didn't solve the feel equation to get that result, did you? If it feels faster, then how can the science you quote be true? In the higher velocity realm that bicycles travel, Newtonian mechanics break down and the theory of feel must be used to measure differences in bicycle speed. QED.
> 
> -R


That's right. You have to use the following equations for feel, where x, y, t are the distances in cartesian space from your current position to your next postion, at time, t. x',y',z' are how far the distances SEEM to feel; c is the speed you feel like you should travel if you had all the best kit; and v is the speed you're sure your travelling now because of the component you just mounted.

As you can see when v=c, the denominator goes to 0 and your travelling infinitely faster than you ever could have if you had been on lame-azz bike bits. What's really cool is that if v>c, then x' and t' become imaginary, and you enter a dimension where only Eddie Merckx, Hinault, Coppi, and Charlie Gaul can exist.


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## Anti-gravity (Jul 16, 2004)

*Lmao*



alienator said:


> That's right. You have to use the following equations for feel, where x, y, t are the distances in cartesian space from your current position to your next postion, at time, t. x',y',z' are how far the distances SEEM to feel; c is the speed you feel like you should travel if you had all the best kit; and v is the speed you're sure your travelling now because of the component you just mounted.
> 
> As you can see when v=c, the denominator goes to 0 and your travelling infinitely faster than you ever could have if you had been on lame-azz bike bits. What's really cool is that if v>c, then x' and t' become imaginary, and you enter a dimension where only Eddie Merckx, Hinault, Coppi, and Charlie Gaul can exist.


I've always loved physics humor and cycling humor in their own regard, but when you combine the two, you reach a whole new order of magnitude of hilarity. I can't tell if I'm crying tears of laughter or joy.


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## weiwentg (Feb 3, 2004)

MShaw said:


> Wow! Several posts and no religious argument.
> 
> What's the world coming to?!
> 
> ...


relax, the religious argument has erupted.

I think that tubies do have a clear advantage in cyclocross, because they can be run at significantly lower pressures without pinch-flatting. on the road, I had one set of Zipp 303s with Tufo tires. I never felt that fast on them, and I convinced myself that I wasn't worthy. I switched to a set of semi-aero clinchers with Michelin Pro Races. I've always felt that the Pro Races were very fast tires, nice to see that quantified.


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## jroden (Jun 15, 2004)

OK, riddle me this-- in the winter, I use a clincher, flat-proof tire called the Specialized Armadillo. It uses a very thick cross section with a real hard rubber compnd. It seems to hardly flex at all and rides like a garden hose.

My question is what makes this tire roll so slowly? When I ride downhill in a goup, i quickly lose 10 bike lengths, it's really pronounced. It is a heavy tire, but I'm guessing the lack of any sort of casing flex is the cause? Any ideas why this would be, I wonder about it a lot, I can't imagine there is a slower tire on the market, though it won't flat on you.


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## alienator (Jun 11, 2004)

jroden said:


> OK, riddle me this-- in the winter, I use a clincher, flat-proof tire called the Specialized Armadillo. It uses a very thick cross section with a real hard rubber compnd. It seems to hardly flex at all and rides like a garden hose.
> 
> My question is what makes this tire roll so slowly? When I ride downhill in a goup, i quickly lose 10 bike lengths, it's really pronounced. It is a heavy tire, but I'm guessing the lack of any sort of casing flex is the cause? Any ideas why this would be, I wonder about it a lot, I can't imagine there is a slower tire on the market, though it won't flat on you.


More than likely the same thing that causes rolling resistance to go up on the road when you run high pressures: instead of conforming to the road surface, the tire strikes and hopes over road irregularities.


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## Mark McM (Jun 18, 2005)

*Hysteresis losses*



jroden said:


> OK, riddle me this-- in the winter, I use a clincher, flat-proof tire called the Specialized Armadillo. It uses a very thick cross section with a real hard rubber compnd. It seems to hardly flex at all and rides like a garden hose.
> 
> My question is what makes this tire roll so slowly? When I ride downhill in a goup, i quickly lose 10 bike lengths, it's really pronounced. It is a heavy tire, but I'm guessing the lack of any sort of casing flex is the cause? Any ideas why this would be, I wonder about it a lot, I can't imagine there is a slower tire on the market, though it won't flat on you.


The majority of tire rolling resistance losses are due to hysteresis in the tread and casing (also called hysteresis damping). Energy that goes into flexing the tread and casing is not returned when the tire is un-flexed, and this energy is lost to heat instead. A thick tread and casing generally takes more energy to flex, so more energy is lost in a heavy, thickly treaded tire than in lightweight, thinly treaded tire.

(As a side comment, new tires typically have more rolling resistance than used tires. As the tire wears and the tread gets thinner, it takes less energy to flex it, and hence less energy is lost. In addition, worn tires typically develop a "square" profile at the tread wears from a rounded to a flat shape. This flatter shape flexes less to conform to the ground, and also generates a lower rolling resistance.)


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## Bocephus Jones II (Oct 7, 2004)

jeebus folks--68 replies to this? Isn't the choice between tubies and clinchers pretty clear?


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## Mark McM (Jun 18, 2005)

*Exagerations*



psi_co said:


> You don´´t win today with a 36 roundspokes wheel, over a Zipp 303 or even a Cosmic elite wheelset.
> 
> A 350$ Comsic set will get your breakaway to the finsh-line a 36 spokes wheel won´t even get you making breakaway.
> 
> ...


Okay, I have to call BS here. Firstly, you've completely made up these numbers - 36 spoke wheels don't even take 100 Watts at 47 km/h (more like less than half of that), let alone take up 100-200 Watts more than a Rolf or Bontrager wheel: Analytic Cycling comparision of drag on 32 spoke wheels vs. Specialize Tri-Spokes 

And yes, pro cyclists do win on 36 (or at least 32) spoke wheels today. Here's Tom Boonen doing just that:
Tom Boonen winning 2005 Paris-Roubaix on 36 spoke wheels 

Here's another picture from the same race, where you can count the spokes on several cyclist's wheels (and most of them are on 32 or 36 spoke wheels):
Top euro pros on 36 spoke wheels  

Care to wrong some more?


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## FTF (Aug 5, 2003)

Bocephus Jones II said:


> jeebus folks--68 replies to this? Isn't the choice between tubies and clinchers pretty clear?


So tubies then?


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## FTF (Aug 5, 2003)

Mark McM said:


> Okay, I have to call BS here. Firstly, you've completely made up these numbers - 36 spoke wheels don't even take 100 Watts at 47 km/h (more like less than half of that), let alone take up 100-200 Watts more than a Rolf or Bontrager wheel: Analytic Cycling comparision of drag on 32 spoke wheels vs. Specialize Tri-Spokes
> 
> And yes, pro cyclists do win on 36 (or at least 32) spoke wheels today. Here's Tom Boonen doing just that:
> Tom Boonen winning 2005 Paris-Roubaix on 36 spoke wheels
> ...


Then there's these two loosers: 










Seriously. WHAT where they thinking!


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## SEK82089 (Dec 19, 2004)

FTF said:


> Yes, but not at the same speed, what about if you were in the last lap etc?


I am with you. I pretty much only ride tubular tires and got second place in a sprint with a half flat tire. The course was 4 laps around 6.5 miles country roads so when I heard my tire losing air half way around the last lap I wasn’t stopping. At the end of the race there was maybe 50 PSI in the tire and when I got to my car it was flat. I love tubulars and will always ride them. Training on tubulars isn’t a problem because I can change a tire out in less than 5 minutes. Why do people make such a big deal about gluing tires? I watched my mechanic do it once and read Park tool’s web site and completely understood how to do it and have never had a bond fail. The ride of a tubular is like no other. I wouldn’t ever trade my Continental tubular tire in for the lightest clincher wheel set and tire combo. All my tires are aged at least a year and ride very forgivingly even at 150 PSI. My father rides tubulars and he past his wisdom on to me. Check out nimble.net (tubular advise) for other reasons why tubulars are better than clinchers.


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## psi_co (Sep 27, 2004)

A 32-26 spokes wheel with bladed spokes is pretty damn aero, I was more referring to a roundspoke wheel.

Nonetheless, race-riders are pretty traditionally boundend to the materials used, as are the mechanics, etc. which doesn´t mean a 16 spoke deep section wheel would´nt be the better choice even for Paris-Roubaix.-STI´s needed some time for their acceptance in the peloton as did the clipless, as did ... .

The watt-measuers were just a guess, I´ve read a test where the aerodynamically worst wheel /sinergy spox, measured 413 watt at 45Km/h, while the best wheel, which was a Hed Trispoke, needed 381watts for the whole system bike/rider on a 
indoor track, measured with srm-cranks, bike equipped with aero-bars.

When it comes to crosswinds the drag will be even more pronounced;while specially designed wheels will even reduce drag, by sailing along, traditional wheels will be just pushed away while you´re peddeling against the force working on your spokes.

All right, I was wrong with 100 watts (was I?), but even 20-30 watts more could be the make or breake.


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## Friction_Shifter (Feb 8, 2006)

Cross section of clincher vs. tubular.

Tubular:The entire cross section provides mechanical integrity (to keep wheel true for example).

Clincher: The outer-most regions on both sides provide a braking surface but do not provide as much mechanical integrity (added weight that is not strengthening the rim as efficiently as say a tubular rim for example).

My vote is for tubulars. Mounted properly and inflated properly one does not need to worry about tubulars rolling off. I think they offer a better "road feel" too.


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## homebrew (Oct 28, 2004)

IMO My $3000 wheels only pay off at higher speeds and when your at Starbucks however I should state that after dropping that much coin I can't let somebody on 32 spoke wheels pass me can I. This alone gives me 2kph  I love the way Boras fly on downhills and set a personal best last week. They are faster on the flats and with a headwind they help abit. They do not make me climb much faster but what the heck. I notice it most when I switch from my Ky's. Models are great but the leave out some much important data. The roads I ride hace bad sections, steep sections. gravel and all sorts of things that slow me down. Meaning that I then have to pick up the speed over and over. I get wind from all directions, sometimes rain. I have yet to see a model that takes this all into account. It does not take into account that I had just enough left on a climb to catch my mates wheel. Please understand that I also love the analytical.com site but its just modeling. Plecebo effect? damn straight, I take any legal advantage when I race. IMO good wheels are the best money you can spend on a bike. They may not be carbon areo models, maybe open pros are the best for your needs and thats cool. Figure out what your type of riding requires and buy the best you can afford.


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## dshefner (Mar 19, 2006)

*my .02*

I'm new to this stuff, so don't be flamin' me. I have been riding michelin pro2race on ksyrium sl2's for 9 months at 118-120psi. I recently purchased, Zipp 303 tubulars w/ Conti Sprinters running at 150psi. I know that sounds high in the pressure department, but I love the feel of the tubulars(or the carbon rims), I have noticed the light feel as I accelerate up climbs, the initial snap in the sprint, not to mention it took 1.2 lbs of rotational weight off my bike. It was weighed with ksyrium/michpro2ace 15.8lbs. Then changed over to the Zipp 303 w/conti sprinters 14.6lbs. 
That being said, if I can keep a few tubie's in reserve and stetched, I would ride them all the time. Not sure if my wallet is that large, and still afford to race every weekend. 
I like both, the convienence of the clinchers......the road feel of the tubulars...
I plan to keep both handy and ready.......
 Ride what feels good and you like.


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## olddog (Dec 5, 2004)

No flames, just a gentle recommendation. You'll actually be faster (assuming that your not doing a majority of your riding on a wooden track) with lower tire pressure. The experts recommend between 105 - 120 for tubies, and around 95-105 for clinchers, depending on road surface and rider weight. Lower pressure lets your tires conform to the small irregularities of the road surface, while the high pressures you're running will actually cause very small but very real vertical movement of the entire bike and rider. It feels faster, but only because your body intrepretes that extra vibration as increased speed. It's the same reason that a fully rigid or hardtail mountain bike "feels" faster than a fully suspended one. Faster + more comfort with no added expense - such a deal.



dshefner said:


> I'm new to this stuff, so don't be flamin' me. I have been riding michelin pro2race on ksyrium sl2's for 9 months at 118-120psi. I recently purchased, Zipp 303 tubulars w/ Conti Sprinters running at 150psi. I know that sounds high in the pressure department, but I love the feel of the tubulars(or the carbon rims), I have noticed the light feel as I accelerate up climbs, the initial snap in the sprint, not to mention it took 1.2 lbs of rotational weight off my bike. It was weighed with ksyrium/michpro2ace 15.8lbs. Then changed over to the Zipp 303 w/conti sprinters 14.6lbs.
> That being said, if I can keep a few tubie's in reserve and stetched, I would ride them all the time. Not sure if my wallet is that large, and still afford to race every weekend.
> I like both, the convienence of the clinchers......the road feel of the tubulars...
> I plan to keep both handy and ready.......
> Ride what feels good and you like.


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## dshefner (Mar 19, 2006)

olddog said:


> No flames, just a gentle recommendation. You'll actually be faster (assuming that your not doing a majority of your riding on a wooden track) with lower tire pressure. The experts recommend between 105 - 120 for tubies, and around 95-105 for clinchers, depending on road surface and rider weight. Lower pressure lets your tires conform to the small irregularities of the road surface, while the high pressures you're running will actually cause very small but very real vertical movement of the entire bike and rider. It feels faster, but only because your body intrepretes that extra vibration as increased speed. It's the same reason that a fully rigid or hardtail mountain bike "feels" faster than a fully suspended one. Faster + more comfort with no added expense - such a deal.



Thanks I'll give it a try starting today..


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## [email protected] (Feb 7, 2006)

you guys are going way overboard with the science stuff!!
I completely agree with the placebo effect, and its real benefit (ie. its a good thing).

For those who have an opinion about tubulars without even having tried them, do yourself a favour and -try- them. You can build a tubie wheelset very cheap, $14 Campy Omega rims from Nashbar, any 10 speed hubset (Ultegra/DA/Chorus/Record/AC, etc.) and revos up front, double butted on back, 28 spoke, conti sprinters. Built right, they'll feel stiff and fast. BTW, I weigh up to 185, and have never had any 28 spoke wheels I've built go out of true more than a couple mm's, thats the honest truth.
At least then you'll be able to say you tried them. Best case, you love them, worst case, you take them apart and rebuild onto clincher rims. In either case, you'll have better wheels than most pre-builts...
I've been riding for 16 years, and have flip flopped a couple of times, but always returned to tubies. Gluing them is a joke once you know how (if it takes you an hour, and you have glue all over the place, then you don't knw how.), as is changing them on the road.

Someone said you need a follow car if you ride tubies??? lol! You can easily fold up two spare tubies under a saddle.
Someone said expensive? Sprinters can be had for $35. Competitions (which are awesome) can be had for about $55 each.
Hell, if you spent 3k plus on your bike, you kind of owe it to yourself to try something that might make a lot more difference in your ride than those carbon bars/stem/seatpost that you blew your money on!


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## rruff (Feb 28, 2006)

homebrew said:


> Plecebo effect? damn straight, I take any legal advantage when I race.


The placebo effect only works if you *believe* in it... which I guess is why all of you who have invested in your personal placebos are so vehemently protesting the facts. If you want every legal advantage, then choose the components that really *are* faster... and placebo on that!

Regarding tubulars and rolling resistance... if a hard (track) glue is used, then tubulars would probably be better than clinchers. I'm not familiar with the stuff, but possibly the pros are using this. 

I'd personally like to thank all of you (Mark McM especially) who have tirelessly and clearly explained what the facts are regarding rolling resistance and rotating weight, etc. Bookmark this thread so that the next time the subject comes up we won't have to go through this all over again.


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## [email protected] (Feb 7, 2006)

[email protected] said:


> you guys are going way overboard with the science stuff!!
> I completely agree with the placebo effect, and its real benefit (ie. its a good thing).
> 
> For those who have an opinion about tubulars without even having tried them, do yourself a favour and -try- them. You can build a tubie wheelset very cheap, $14 Campy Omega rims from Nashbar, any 10 speed hubset (Ultegra/DA/Chorus/Record/AC, etc.) and revos up front, double butted on back, 28 spoke, conti sprinters. Built right, they'll feel stiff and fast. BTW, I weigh up to 185, and have never had any 28 spoke wheels I've built go out of true more than a couple mm's, thats the honest truth.
> ...


BTW, just did a quick calculation of my last handbuilts using the parts I mentioned above (Campy omega tubulars, AC 10 speed hubset, revolution 2.0/1.5 x 28 on front, DT competition 1.8/1.6 x 28 on rear, alloy nips all around except brass on drive side rear).
Weight without skewers or tires or cassette = ~1440 grams. Thats lighter than Ksyriums.
And you could get lighter by using lighter spokes.
Total cost was about $220 including a set of skewers that came with the hubs.


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## handsomerob (Oct 5, 2005)

I read just about this whole thread and my head is still spinning, but I have a specific question regarding the rotational weight issue.

Wouldn't riders who do not spin very well (like myself) benefit more from a reduced rotational weight due to the micro acceleration differences derived from the alternating 2 major pedal strokes of your revolution? In essense having two accelerating and two decelerating periods with every revolution of your crank. Although your actual velocity might not vary more than a few tenths or hundreths wouldn't more than 1/2 of your pedal stroke be spent on true acceleration.

I have wrapped my head around the idea that at a "constant" speed, rotational weight makes very minimal difference, but who is pedalling at a truely constant speed without acceleration? As far as "engine" smoothness goes, I would think a dual piston engine (insert rider here) would not be a very constant propelling force. Combine that with the increased inertia? required to complete a revolution on a much less smooth uphill climb, where many riders have to get out of the saddle and 1 2 mash their way to the crest. I wonder how long it would take to develop a good smooth spin technique while out of the saddle.

edited to add.....I would think the periods of acceleration and deceleration climbing a hill would be much more pronounced with less (shorter) "maintainence" energy. For instance... and this is anything but scentific.... 

Let's say you are pedalling a slow (but mathmatically easy) cadence of 60 with each full revolution of your crank taking 1 full second.

Say the downstoke of your drive side crank arm takes 4/10 a second as does the downstroke of your non-drive side crank arm. 

The "lull" or transitional period where the stroke is not as smooth (which I am sure would not be near as pronounced with a pro rider) is a tenth of a second on each side.

So here we are with 8/10 of a second spent on downstrokes of each piston and 2/10 of a second on the "transitional" time. 

Assume the 3 of the 4 tenths on each downstroke is spent accelerating and 1 of the 4 tenths on the downstroke and the tenth of transitional time is spent decelerating. (there would be two much smaller fractions of a second where there would be neither acceleration or deceleration) 

Wouldn't that mean we have spent 60% of our revolution as acceleration and 40% as deceleration? Surely at least on a micro level?

Does this then mean that rotational weight could be more important than formulas that use "constant" speed prove?


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## alienator (Jun 11, 2004)

handsomerob said:


> I read just about this whole thread and my head is still spinning, but I have a specific question regarding the rotational weight issue.
> 
> Wouldn't riders who do not spin very well (like myself) benefit more from a reduced rotational weight due to the micro acceleration differences derived from the alternating 2 major pedal strokes of your revolution? In essense having two accelerating and two decelerating periods with every revolution of your crank. Although your actual velocity might not vary more than a few tenths or hundreths wouldn't more than 1/2 of your pedal stroke be spent on true acceleration.
> 
> ...


In a nutshell, no. Since you brought up the 2 cyl. motor thing, I'll use that to explain why. 2 cyl. engines use a flywheel to keep energy up through out the power cycle. The purpose of that flywheel is to store energy, and how much energy it stores is a function of how fast the flywheel is spinning (squared) and the moment of inertia of the flywheel. Flywheels typically have a pretty significant moment of inertia. If you don't understand what moment of inertia is, then just consider to be a measure of how unwilling the flywheel is to change it's motion. So because of the flywheel's resistance to acceleration, twin's don't rev up as fast as 4 cylinders. But at the same time, they don't lose rpms as fast off the gas (ok, this doesn't take into consideration compression ratio in the cylinders.). Having spent more than a few years racing twins, I can tell you they behave just like I described. The same bike, without a flywheel, spun up faster than it did with the flywheel, but it also lost revs more quickly. Overall this smooths out the power cycle a bit.

On bicycle, the wheels are the flywheels. As such wheels with high moments of inertia....heavy at the rim.....will not decelerate as much through a pedal cycle as wheels with a smaller moment of inertia will (light at the rim). In fact those "micro" accelerations, which are pretty much insignificant anyway, will be even less of a factor on a wheel that's heavy at the rim. It'll take more energy to spin up the wheel with higher moment of inertia, when you start at zero and accelerate, but that happens very little on a ride. All of this is backed up by studies and results. In fact until the grade gets really steep, aero concerns are the big concerns. It's only after the grade becomes steep that wheel weight/inertia surpasses aero. Even then, it's not likely a huge factor.

The real benefit to a lighter wheel, aka one with a low moment of inertia, would be in energy conservation over the course of a long day with lots of climbing or lots of pedaling into the wind. Even then, the difference may not be huge. I think it'd be big enough to make a difference in how you feel in the end, maybe could be the difference between bonking and not, but that would depend greatly on the person in question.


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## rruff (Feb 28, 2006)

alienator said:


> The real benefit to a lighter wheel, aka one with a low moment of inertia, would be in energy conservation over the course of a long day with lots of climbing or lots of pedaling into the wind. Even then, the difference may not be huge. I think it'd be big enough to make a difference in how you feel in the end, maybe could be the difference between bonking and not, but that would depend greatly on the person in question.


You were doing so well until you got to that paragraph!... then you seemed to wander from the True Path...

Mark McM and I have both looked at this micro rotational inertia thing in nausiating detail and concluded that *higher* inertia is a slight benefit... very very slight... but still in favor of higher inertia in *all* "constant" speed situations (where there isn't a net increase or decrease in speed). Of course, on a climb it is nice to have low weight, but if you have to have it somewhere, it might as well be on the wheels. If you are in a situation where you have to do a lot of hard accelerating over and over again, then lower inertia would be helpful... but that only happens when you are at the wrong end of a crit field on a tight course... and if you stay there, you won't be in danger of winning anyway.

Handsomerob... This was hashed over and over on most of the bike forums recently, so if you do a search you should be able to find plenty of light reading.


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## alienator (Jun 11, 2004)

rruff said:


> You were doing so well until you got to that paragraph!... then you seemed to wander from the True Path...
> 
> Mark McM and I have both looked at this micro rotational inertia thing in nausiating detail and concluded that *higher* inertia is a slight benefit... very very slight... but still in favor of higher inertia in *all* "constant" speed situations (where there isn't a net increase or decrease in speed). Of course, on a climb it is nice to have low weight, but if you have to have it somewhere, it might as well be on the wheels. If you are in a situation where you have to do a lot of hard accelerating over and over again, then lower inertia would be helpful... but that only happens when you are at the wrong end of a crit field on a tight course... and if you stay there, you won't be in danger of winning anyway.
> 
> Handsomerob... This was hashed over and over on most of the bike forums recently, so if you do a search you should be able to find plenty of light reading.


Ah, but I said it be a small difference after a long day. Didn't say nuthin' contrary to good ol' physics.


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## Mark McM (Jun 18, 2005)

*Falling down into the "energy to accelerate" hole*



handsomerob said:


> ... Although your actual velocity might not vary more than a few tenths or hundreths wouldn't more than 1/2 of your pedal stroke be spent on true acceleration.
> 
> I have wrapped my head around the idea that at a "constant" speed, rotational weight makes very minimal difference, but who is pedalling at a truely constant speed without acceleration? ...
> 
> edited to add.....I would think the periods of acceleration and deceleration climbing a hill would be much more pronounced with less (shorter) "maintainence" energy. For instance... and this is anything but scentific....


I think these passages highlight a common misunderstanding about fluctuating pedal torque and "micro-accelerations". Energy used to accelerate the bike (even the "micro-accelerations" from pedal pulses) is *not lost*. It is simply *stored as kinetic energy*. Kinetic energy is the energy of motion, and represented *energy stored by the system*, and is utilized to keep the body in motion when a retarding force is applied. 

In the passage above you refer to using a larger portion of the pedal stroke for "true acceleration". But all accelerations are true accelerations, and store kinetic energy. Afterall, when climbing, the wheels, the bike and you are all going up hill, working against gravity, so any acceleration forward represents work applied to climbing the hill. There is really no such thing as a seperate "maintenance energy", since any extra kinetic energy from a small acceleration is also added to the energy used to push the entire mass up the hill.

Have you ever had a flywheel powered toy, where you pulled a string to accelerate the flywheel, and then when you put the tow down on the ground and it moved under the flywheel's power? What if you had two identical toys, but removed the flywheel from one and substitute a non-rotating mass of the same weight, so the two toys still had the same total mass. Now, wind-up the flywheel in the toy with the flywheel, and then give them both a push up a hill. Which goes up the hill further? The one with the flywheel, of course. The stored energy in the flywheel adds to the energy pushing the toy up the hill, and it goes further. If you were to move non-rotating mass from a bike and put it on the wheels (rotating mass), it would have the same effect as the toy's flywheel - the energy used to accelerate the heavier wheels is not lost, it is simply stored, and helps move the bike up the hill.


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## handsomerob (Oct 5, 2005)

Mark McM said:


> Have you ever had a flywheel powered toy, where you pulled a string to accelerate the flywheel, and then when you put the tow down on the ground and it moved under the flywheel's power? What if you had two identical toys, but removed the flywheel from one and substitute a non-rotating mass of the same weight, so the two toys still had the same total mass. Now, wind-up the flywheel in the toy with the flywheel, and then give them both a push up a hill. Which goes up the hill further? The one with the flywheel, of course. The stored energy in the flywheel adds to the energy pushing the toy up the hill, and it goes further. If you were to move non-rotating mass from a bike and put it on the wheels (rotating mass), it would have the same effect as the toy's flywheel - the energy used to accelerate the heavier wheels is not lost, it is simply stored, and helps move the bike up the hill.



Leave it to a kid's toy analogy for me to "get it"..... that does make sense that the greater energy needed to "spin up" a heavier flywheel is not lost, more it becomes a greater "store" of kinetic energy to continue the forward motion where a lighter flywheel would not have as much kinetic energy stored to continue the motion. 

Now let's take this analogy and what we know about spinning vs. mashing and the effects of each on lactic acid buildup. 

I am understanding that the energy needed to propel different weight flywheels over a distance should nearly be equal in the end as per your explaination. However, with the way the human body functions, wouldn't it be possible that the extra exertion/force/energy used to overcome inertia? and build up the greater kinetic energy in the heavier wheels cross a lactic threshold wear as a lighter wheelset might allow a tighter tolerance on the amount of peak energy required at any given time. Similar to the benefits of a higher RPM/smaller gear vs. a lower RPM/lower gear.

For example say it takes X amount of energy to complete a revolution in the smaller gear and Y in the bigger gear.

Say it takes 100 revoltions of the X to go a certain distance
and only 50 revolutions of Y to do the same, but it takes twice as much energy to complete a Y revolution than an X revolution. 

100 times X = Distance
50 times Y = Distance

energy required for Y revolution is 2 times that of X revolution

Y = 2X
100 (x) = 50 
100 (x) = 50 (2X)
100x = 100x

The total energy needed in this scenario is the same for both combinations, but in the human body, passing a certain exertion threshold becomes disproportionately more difficult (for instance when the body produces lactic acid). 

To assimilate your motor engine/flywheel example.... why would a lighter flywheel be such an important upgrade to make a car perform better if the benefit wasn't significant. I would prefer an easier ability to "spool" up more than the benefit of stored kinetic energy, much like I find it easier to spin than mash.


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## handsomerob (Oct 5, 2005)

rruff said:


> Handsomerob... This was hashed over and over on most of the bike forums recently, so if you do a search you should be able to find plenty of light reading.



If this is light reading for you, then Mensa has a place for you for sure...  

I have read through quite a few threads to get some perspective, but there seem to be a lot of "formulas" that show that the difference isn't there... I find it very difficult to use something as black and white as a formula when combined with something as complex as a human. 

Has there ever been a study involving a group of pro cyclists and the differences in using different equipment. As a regular schmo, so many things can make me faster or slower, but a professional cyclist should be considerably less variable and the placebo effect should be significantly reduced. It would be nice to take enough of them and put together some data on what differences they experienced.


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## rruff (Feb 28, 2006)

handsomerob said:


> To assimilate your motor engine/flywheel example.... why would a lighter flywheel be such an important upgrade to make a car perform better if the benefit wasn't significant. I would prefer an easier ability to "spool" up more than the benefit of stored kinetic energy, much like I find it easier to spin than mash.


Lower inertia *does* make it easier to "spool up"... I don't think anyone is questioning that. In the case of bike wheels the energy difference is quite small but still real and quantifiable. The question is whether the accelerations and decelerations that occur *within* a pedal stroke favor higher or lower inertia... and the answer is... higher inertia is very slightly better. 

When riding at a "steady" speed there isn't any "spooling up" involved or lactic acid issues...when modeling this the power output (and it's variation within the stroke) is identical in both cases. When you are riding at a "steady" speed there is a repeating pattern every 180 degrees of pedal stroke... the speed fluctuates above and below an average. The only thing that lower inertia does for you is *increase* these fluctuations... it doesn't improve your speed or make it easier somehow. Actually, the greater fluctuations in speed within the pedal stroke tend to make you a little bit slower, because the average power to overcome wind resistance is higher.


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## ampastoral (Oct 3, 2005)

handsomerob said:


> If this is light reading for you, then Mensa has a place for you for sure...


forget the "light" reading. after following the thread, i want "aero" reading. i'll meet with less resistance and understand it quicker... of course, if this was published in book form and i wanted to read on my back, then i'd go for the light version....but only then


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## alienator (Jun 11, 2004)

rruff said:


> Lower inertia *does* make it easier to "spool up"... I don't think anyone is questioning that. In the case of bike wheels the energy difference is quite small but still real and quantifiable. The question is whether the accelerations and decelerations that occur *within* a pedal stroke favor higher or lower inertia... and the answer is... higher inertia is very slightly better.
> 
> When riding at a "steady" speed there isn't any "spooling up" involved or lactic acid issues...when modeling this the power output (and it's variation within the stroke) is identical in both cases. When you are riding at a "steady" speed there is a repeating pattern every 180 degrees of pedal stroke... the speed fluctuates above and below an average. The only thing that lower inertia does for you is *increase* these fluctuations... it doesn't improve your speed or make it easier somehow. Actually, the greater fluctuations in speed within the pedal stroke tend to make you a little bit slower, because the average power to overcome wind resistance is higher.


Well said. Now back to my alleged deviation from the golden path. It's agreed any energy changes as a result of acceleration of the wheels is very small. However, given the small, yet quantifiable nature of those energy changes, the most likely place to notice the sum of said changes is at the end of a long day climbing or pedaling into gusty winds. Unlike a bicycle or even a car engine where efficiency can be pretty well quantified, the efficiency of the human corpus can't. Power output varies in a non-linear fashion and efficiency also varies. So in a human decreased power output is not just he result of insuffucient energy reserves, it's also the result of increased inefficiencies in the body due to chemistry changes, etc. Given that, it's possible that any benefit from light wheels with low moments might just be having a bit o' extra gas left in the tank, for that last monster col or having a body that's just a bit more efficient than it otherwise might have been. How this would fall out would be completely dependent on the rider in question, and might only manifest in the rider cresting the col instead of bonking 100 feet before the summit. That said, it'd still be a very small benefit. 

So the sum of what everyone is saying would be that it'd be best for a guy or gal to buy those slick, new HED cast iron deep rimmed wheels, cuz while they'd not kill ya too much on the climb, they'd rail on the descent.


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## ergott (Feb 26, 2006)

Mark McM said:


> At the same time, you might want to ask why almost all tubular tires (including those used by pro teams) have patterned tread, when patterned tread is not only unnecessary on bicycle tires, but both increases rolling resistance and decreases traction.


According to the tests you cite http://www.rouesartisanales.com/article-1503651.html the best tubular tire (Veloflex Carbon) has a tread pattern. Imagine how much it would be without the pattern. I bet a treadless Veloflex would be the fastest tire out there! Maybe the added tread pattern on the good tubulars account for the higher Crr moreso than the fact they are tubulars.

-Eric


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## Mark McM (Jun 18, 2005)

*Tread patterns too small to make a large difference*



ergott said:


> According to the tests you cite http://www.rouesartisanales.com/article-1503651.html the best tubular tire (Veloflex Carbon) has a tread pattern. Imagine how much it would be without the pattern. I bet a treadless Veloflex would be the fastest tire out there! Maybe the added tread pattern on the good tubulars account for the higher Crr moreso than the fact they are tubulars.


The amount of pattern that exists in road tires is very small and shallow, so they have little affect at all. None the less, the small affect they do have is negative on both traction and rolling resistance.

The majority of rolling resistance losses are from the hysteresis of the tire (and tube) flexing as it rolls through the load affected zone at the bottom (both at the ground contact point, and at the rim), and so the rolling resistance is mainly dependent on the type and amount of material used in the tire. All else being the same, the lighter tire will have a lower rolling resistance. The Veloflex Carbon is one of the lighter tires in the test, so it is not surprising that it has a lower rolling resistance. A small amount of pattern in the tread will have only a small (and negative) affect on rolling resistance and traction. In addition, the Veloflex Carbon has a latex tube, which has been shown to have lower hysteresis losses than butyl tubes.

A better comparison to illustrate the difference in rolling resistance between tubulars and clinchers is to compare tires which are nearly identical construction. The Vittoria Corsa EVO CX tubular and Vittoria Open Corsa EVO CX clincher have identical casings and tread, and differ in that the casing of the tubular version has its casing sewn shut and a base tape glued on, while the clincher version has a bead glued into the edges of the casing. And yet, the Corsa EVO CX tubular has a Crr of 0.0055 at 7.5 bar, while the Open Corsa EVO CX clincher has a Crr of only 0.0039 at 7 bar, or about 1/3 lower. The losses through flexing at the ground contact point will be nearly the same for both tires, so the differences are mainly in the flexing at the rim, which is where the two types of tires differ the most.


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