# What's 10 watts anyway?



## BikeLayne (Apr 4, 2014)

I recently decided to try a folding Michelin Pro 4 Endurance 25mm instead of my usual folding Gatorskin 25mm. I have had no complaints with the Gatorskin really and found them to be durable and long wearing tires.

So I bought a single Michelin tire and put it on and it seemed about the same. Maybe a little softer and it handles better but you always experience that when you take off a worn squared off tire.

Anyway I googled around and found a tire review. Rolling resistance and such. The Michelin Pro 4 Endurance has 5.1 watts per tire less rolling resistance then the Gatorskin.

Also the Gatorskin claims 180tpi (actually 3 layers of 60tpi) and the Endurance claims 110 tpi (actually 3 layers of 110tpi). 

The chart is fun to look at to compare some tires that you may have owned or thinking of.

I ordered a 2nd Endurance since it is rated well and they are honest about the tpi information. 

Claimed weight on the Gatorskin is 240 grams and the measured weight is 255grms. The Endurance claims 245 and weights 245.

Road Bike Tires Rolling Resistance Reviews


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## ergott (Feb 26, 2006)

I ride around with my dyno light on all the time. That's 7 watts right there.

I could tell you how turning off the light is like hitting a turbo boost button, but you know that's hogwash.


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## BikeLayne (Apr 4, 2014)

ergott said:


> I ride around with my dyno light on all the time. That's 7 watts right there.
> 
> I could tell you how turning off the light is like hitting a turbo boost button, but you know that's hogwash.


Dyno lights are great. Worth the watts to be able to see for sure..


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## Jay Strongbow (May 8, 2010)

I'm pretty sure with some google skills and a pocket full of money I could find and purchase enough watts savings to make the jump to Cat 1 in 3-5 days. Or overnight but I don't want to pay the extra for overnight shipping so cat 1 can wait a few days.


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## BikeLayne (Apr 4, 2014)

Jay Strongbow said:


> I'm pretty sure with some google skills and a pocket full of money I could find and purchase enough watts savings to make the jump to Cat 1 in 3-5 days. Or overnight but I don't want to pay the extra for overnight shipping so cat 1 can wait a few days.


Well I am just buying durable tires as the old one's wear out.


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## stevesbike (Jun 3, 2002)

the velonews test found that the Michelin Pro 4 service course took 12.5 watts more than the GP4000s II. Even assuming the endurance had the same rolling resistance (which is unlikely) putting on a set of GP4000s would save you 35 watts at 25mph. That's not an insignificant amount....


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## dcgriz (Feb 13, 2011)

The protocols used in the rolling tests are not standardized so drastically different values come out as the result depending how a tire was tested and at what parameters.
Tour magazine did a rolling resistance test on a bunch of popular tires back in the spring of 2014. See how the results vary from the VN test.
http://www.conti-tyres.co.uk/contic...Tests/Wide_Tyre_Test_TourMagazine_2014_UK.pdf
Tour also indicated that testing the tires on rollers tends to exaggerate the resistance values. According to them testing the tires on a flatter surface, like a belt, gives more accurate results. Their test shows the difference between the Conti 4ksii and the Michelin Pro Comp is not more than a few watts. 
So basically choose your poison...


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## ergott (Feb 26, 2006)

I just can't wrap my brain around a 35watt difference between two similar sized, performance tires. It would be another thing if one was something like a Specialized Armadillo and the other a race tire.


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## BikeLayne (Apr 4, 2014)

I guess for me 10 watts might mean something if it could be correlated into a figure of time saved over a course. Say a 2 mile uphill course that took 7min and 28 seconds at 273 watts. So if you convert that to 448 seconds and divide buy 273 then you get 1.6 watts/second. If your goal is to improve 5 seconds would that mean you need 8 more watts or am I in left field.


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## ibericb (Oct 28, 2014)

As dcgriz noted, the differences are very protocol dependent. The more tire deflection a test protocol forces, through drum surface, loading, etc. the greater the difference. Wheel Energy is pretty broadly recognized as being one of the best at testing. That doesn't mean their numbers are any better, just that they are more reliable. IMO, their protocol is designed to show differences more acutely than the protocols of others. That leads to larger differences in the numbers. Which one is more reflective of the real world on the road? That depends on the road, and how you use it). Models are meant to be used, not believed.


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## BikeLayne (Apr 4, 2014)

OK, I was just trying to find out what 10 watts would do anyway. Just theoretical figuring everything else is the same. But it's does not matter as I do not have a power meter anyway and will not be buying one.

In the real world I just like a tire last pretty good and gets a rare flat. One that is not larger then the 25mm Michelin or 5mm Gatorskin so that my fenders will fit. Actually the fenders (SKS P35) are on the bike now as it's been raining. The Michelin should be good but some miles will tell the story.


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## BikeLayne (Apr 4, 2014)

My friend Ben teaches Math and has a power meter and I will ask him my 10 watt question when I see him at the next ride. He will know the Math. Thank you all for your comments.


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## deviousalex (Aug 18, 2010)

Well, we could have had this discussion in the thread started about the VeloNews article two days ago but I guess people don't look before they post.

Anyways, I'm surprised by the results. Even if they are off 20% me running Lithion 2s vs. all my buddies running GP4000S means I'm at a real deficit when the speeds go up. I'm starting to re-think my choice and maybe start springing for the GPs.


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## ibericb (Oct 28, 2014)

The power-force-velocity relationship is pretty simple:

P = F x V

When a tire rolling resistance comparison is made stating Watts as the measure of rolling resistance, which is a force that has to be overcome, there has to be an attendant speed. The recent VeloNews article used 40 km/h (24.9 mph). The Bicycle Tire Rolling Resistance site you noted in the OP uses 29 km/h (18 mph). If you compare the two you will see the power differences between the same tires is greater in the VeloNews article than the the Bicycle Tire... site, in part because it tests at a higher velocity, and also because the VeloNews tests were run at a higher load (50 kg vs. 42.5 kg). Those differences will explain, however, only a fraction of the differences between the results of the two sites. Bear in mind that the difference is per tire, so double it for total effect.


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## Srode (Aug 19, 2012)

10 watts difference for a pair of tires at 25mph, or even if it's half that say climbing a couple mile grade at half the speed can be significant. That's enough to make the difference between getting to the top of our long climb first or 4th place in the group I ride with every morning, or holding on to a tire in a hot pace line in a fast century ride when your legs are fading. If you are already training hard, how much more work is needed to gain 5 or 10 watts in FTP or VO2 max?


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## ibericb (Oct 28, 2014)

For a 190 lb total load bike+rider+gear, typical CdA, riding on the hoods a 10 Watt difference, 260W vs. 250W:

- a difference of 21.6 and 21.2 mph on the flats, no wind 
- a difference of 9.37 vs 9.06 mph on a 6% gradient
- the difference between a 6% and 6.27% gradient climb @ 9.06 mph
- the difference between a headwind of zero vs. 0.5 mph on a flat road @ 21.25 mph

Double that to 20 W, 270W vs 250W:
- a speed difference of 21.9 vs. 21.2 mph flats, no wind
- a difference of 9.69 vs 9.06 mph on a 6% gradient
- the difference between 6% and 6.54% gradient climb @ 9.06 mph
- the difference between a headwind of zero vs 1.0 mph on a flat road @ 21.25 mph

Numbers via Bike Calculator.


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## cnardone (Jun 28, 2014)

So on my early morning solo ride to be healthy, 10 watt's doesn't mean much. In a truly competitive situation, 10W per tire over mixed terrain could be more than .5 MPH. So pretty big.


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## Jay Strongbow (May 8, 2010)

BikeLayne said:


> Well I am just buying durable tires as the old one's wear out.


Not sure if you got my point.

10 watts matters on paper. But if you add up all the claimed watts savings out there and buy them the theory will not match the reality. The theory is that I could get better tires, aero rims, skin suit, aero fram and all that jazz and on paper according to published watts advantages compared to what I currently use the extra watts would put me in cat 1 if not tour pro. However, the reality is I'd still be a schmuck. 
So for practical purposes the difference between 2 tires tested at 10 watts apart isn't going to matter to you.


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## BikeLayne (Apr 4, 2014)

"Numbers via Bike Calculator. "


Thank you, that's was what I was lookin for. Actually more as I was just lookin for the math but this is great.


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## November Dave (Dec 7, 2011)

10 watts is a lot in a race. Over the course of a 3 hour race, that's a lot of energy you haven't spent and can use at the end. It's an amount that a well-trained cyclist would train his/her privates off to gain at threshold. 

It's a bit of a stretch to think that one could buy enough aero to move up a category or three. First, because bike races aren't just fitness contests. Riding smart saves more energy than all the aero gear in the world, knowing when you need to smash and when you can mellow counts for a ton, and bike handling is important. When I raced my first 1/2/3 crit I was in CRAZY good shape and had all I could do to stay in the race. Now, I don't need to be in very good shape to sleepwalk my way into a pack finish in most 1/2/3 crits, just because I'm way better at racing than I was then.

The other big element that puts the lie to buying your way to a higher category is that most people at the races already have all the goodies.


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## ibericb (Oct 28, 2014)

BikeLayne said:


> ... Actually more as I was just lookin for the math but this is great.


If you want the full-on math treatment, see "Validation of a Math Model for Road Cycling Power, by Martin, _et al_, available as a scanned pdf image here. Just solve for Vg if that's what you want to know.


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## BikeLayne (Apr 4, 2014)

Jay Strongbow said:


> Not sure if you got my point.
> 
> 10 watts matters on paper. But if you add up all the claimed watts savings out there and buy them the theory will not match the reality. The theory is that I could get better tires, aero rims, skin suit, aero fram and all that jazz and on paper according to published watts advantages compared to what I currently use the extra watts would put me in cat 1 if not tour pro. However, the reality is I'd still be a schmuck.
> So for practical purposes the difference between 2 tires tested at 10 watts apart isn't going to matter to you.


I do get your point however I was just looking for the math. I am not interested in buying more speed. The faster I ride the sooner I have to pull weeds or empty the dishwasher.


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## BikeLayne (Apr 4, 2014)

ibericb said:


> If you want the full-on math treatment, see "Validation of a Math Model for Road Cycling Power, by Martin, _et al_, available as a scanned pdf image here. Just solve for Vg if that's what you want to know.


 I will pass on that one, but the calculator is great.


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## Jay Strongbow (May 8, 2010)

November Dave said:


> 10 watts is a lot in a race. Over the course of a 3 hour race, that's a lot of energy you haven't spent and can use at the end. It's an amount that a well-trained cyclist would train his/her privates off to gain at threshold.
> 
> It's a bit of a stretch to think that one could buy enough aero to move up a category or three. First, because bike races aren't just fitness contests. Riding smart saves more energy than all the aero gear in the world, knowing when you need to smash and when you can mellow counts for a ton, and bike handling is important. When I raced my first 1/2/3 crit I was in CRAZY good shape and had all I could do to stay in the race. Now, I don't need to be in very good shape to sleepwalk my way into a pack finish in most 1/2/3 crits, just because I'm way better at racing than I was then.
> 
> The other big element that puts the lie to buying your way to a higher category is that most people at the races already have all the goodies.


You're claim that it's a stretch (on paper, it's more than just a stretch in reality) rests on the assumption that the person buying the stuff doesn't know how to race. That might be a stretch.

Obviously (I would have thought) I was talking about all else being equal. And equally obvious (I thought) was that I didn't literally think I could buy my way into cat 1 but was trying to show that aero and other watts savings you see on the internet don't translate to the road because there is no way in heck I could jump to cat 1 despite being able to google and find the wattage jump, on paper, that I'd need to get that much faster.

Your last point is N/A because the person theoretically buying the stuff off course doesn't already have it.

Another way to look at it is that the cat 1 guy who has all the goodies would suddenly be a cat 3 if the watts savings he has, on paper, were taken away. We all know that wouldn't happen.


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## dracula (Mar 9, 2010)

stevesbike said:


> the velonews test found that the Michelin Pro 4 service course took 12.5 watts more than the GP4000s II. Even assuming the endurance had the same rolling resistance (which is unlikely) putting on a set of GP4000s would save you 35 watts at 25mph. That's not an insignificant amount....



People have argued though this would only apply to you riding your tyre on a steel drum where by contrast real road conditions would render any rolling resistance test futile.

However, people have also argued the steel drum values will translate into real world conditions; a fast tested tyre will gonna be fast no matter the road.

I cannot believe the Velonews article. Not for Michelin. I mean they are not just road tyre manufactures and I would expect a trickle down effect from their car tyre research department to the road tyre design team. Michelin as no other will have all the testing facilties in the world and it does not take a brain to test their own tyres against some market leading competitors. Repeat with new rubber formula and test again.


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## SauronHimself (Nov 21, 2012)

Ten watts could make or break a race, but during a commute or a casual ride 10W and $5 will get you a Big Mac at McDonalds.


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## BikeLayne (Apr 4, 2014)

The calculator is awesome but some data I cannot enter as I do not know. I do not know about the side wind and what to enter. Trans efficieny I assume is Transmission of power which I do not know. Anyway I kind of manipulated those numbers a bit until I arrived at the time I actually rode the segment and then duplicated the numbers with the change of 10 more watts. The calculator gave me an extra 15 seconds and my basic ratio that I initially used gave me 8 more seconds. I will use my ratio if I ever revisit this idea. Anyway basically 10 watts seems to make a difference. 

Anyway it's not necessary to revisit the Math for me but if the thread moves into some other direction that is cool. I was just curious if 10 watts would make a difference and It seems that it does. On the flipside I am not one to waste money and have no interest in buying more speed. 

I had always wondered why the Pro's do not use a more durable tire thinking they would be faster if they did not have to stand around when they flat. But 10 watts would be a big deal when racing all day.


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## November Dave (Dec 7, 2011)

The unfortunate thing is that a lot of people do believe that you can but your way into a higher category. The far more unfortunate thing is the inverse of that - that people believe it makes no sense to even try racing if you've having got the latest flashy flashy. That's the crux of my last point - if everyone from Cat 1 to Cat 5 is paying attention to all of these "buyable gains," they're not a relative advantage for anyone. 

I actually thought that you weren't at all talking about all else being equal - my read was "here I am, as I am. Gonna get me a speedy helmet/tires/wheels/bike and look out cat 1!" Because there are plenty of people out there with that impression, and plenty of entities not entirely trying to disabuse people of that notion. That difference cleared up, I think we're in somewhat violent agreement that your credit card isn't going to get you into a different category.


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## Jay Strongbow (May 8, 2010)

November Dave said:


> The unfortunate thing is that a lot of people do believe that you can but your way into a higher category. The far more unfortunate thing is the inverse of that - that people believe it makes no sense to even try racing if you've having got the latest flashy flashy. That's the crux of my last point - if everyone from Cat 1 to Cat 5 is paying attention to all of these "buyable gains," they're not a relative advantage for anyone.
> 
> I actually thought that you weren't at all talking about all else being equal - *my read was "here I am, as I am. Gonna get me a speedy helmet/tires/wheels/bike and look out cat 1!"* Because there are plenty of people out there with that impression, and plenty of entities not entirely trying to disabuse people of that notion. That difference cleared up, I think we're in somewhat violent agreement that your credit card isn't going to get you into a different category.


good Lord no, you have my permission in advance to shoot me if I ever claim that and really mean it.

Just a miscommunication then. yup, we agree completely. Good point about the people who think they 'need' all that stuff so don't race. That is sad.


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## BikeLayne (Apr 4, 2014)

Around here it's all about cyclocross. They guys just race on whatever they can afford. However they seem to prefer 28mm tires for the road. They just change out the tires on Monday and ride that way until the next Sunday which is race day.


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## ibericb (Oct 28, 2014)

November Dave said:


> The unfortunate thing is that a lot of people do believe that you can but your way into a higher category.


If a decent cyclist could actually buy all the reported time shaved off a 40 k TT from each new lower drag / lower RR / lower weight improvement that has come out in the last two years, and add those up, I think (s)he might be able get save more time than they would otherwise realize, meaning they would be done before they even started.


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## November Dave (Dec 7, 2011)

Yes, the time/space continuum takes a beating with some of these reports, doesn't it? Hence my "some entities not exactly trying to disabuse people of these notions" thing. I mean, there's some "there" there, but nowhere near as much as you could easily conclude that there is.


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## dracula (Mar 9, 2010)

ibericb said:


> If a decent cyclist could actually buy all the reported time shaved off a 40 k TT from each new lower drag / lower RR / lower weight improvement that has come out in the last two years, and add those up, I think (s)he might be able get save more time than they would otherwise realize, meaning they would be done before they even started.


I think what would be interesting for most of us:

Given our current set-up and fitness level. 

Meet the professional Tour de France fitter - not round the corner local bike shop fitting expert - and let him tell you how much you could save in terms of minutes or seconds on your next century ride by (money no objection):

a) swapping out and replacing parts including wheels
b) working on your position in the wind tunnel

I'd really like to know.


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## Notvintage (May 19, 2013)

stevesbike said:


> . . .putting on a set of GP4000s would save you 35 watts at 25mph. That's not an insignificant amount....


It is to 99.5% of anyone on this forum. If you're not a pro riding for food who cares really?


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## ziscwg (Apr 19, 2010)

If you get your watt saving tires and I pass your a$$ on the climb like you're standing still, did you get your moneys worth?

Sometime we over analyze all these numbers and device that are better. Yet, we don't look in the mirror and try to figure out how to improve what we see.


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## stevesbike (Jun 3, 2002)

November Dave said:


> Yes, the time/space continuum takes a beating with some of these reports, doesn't it? Hence my "some entities not exactly trying to disabuse people of these notions" thing. I mean, there's some "there" there, but nowhere near as much as you could easily conclude that there is.


kind of ironic coming from someone selling wheels on the basis of aerodynamic savings. If other reports use similar methodology (or better yet utilize testing on the entire system - rider/bike/wheel interaction rather than an isolated component) then why are their results any less valid than your claims about your wheels? What specific results are invalid? Are the advantages someone can accrue via an aerodynamic frame, helmet, skinsuit, wheels, arm/leg shaving, etc. not real ones? Why does Bouhanni wear a skinsuit on a 5 hour Tour stage? Maybe because it could be the difference between winning and losing?


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## November Dave (Dec 7, 2011)

Semantically, it's much more contradictory than ironic. And to say that we sell wheels on the basis of aerodynamic savings is only part of the picture. We sell one set of wheels that has a significant aerodynamics component - the Rail 52. When we launched that, we went to great pains to compare it to a relevant comparative choice, specifically the Zipp 404. We didn't go out and find the biggest punching dummy we could and show a huge yawning gap of time savings against it, as was overwhelmingly the convention at the time and is still a popular method. We also did the correct thing and made all comparisons in the same wind tunnel at the same time with the same tire (not tires, tire). There are plenty of charts out there that compare tests from different times, different tunnels, different protocols, etc. One company compares their wheels at tared values against runs that were done at a different time with the values left untared. At every step, we've tried to be as specific, transparent, and applicable as possible. 

We've also been very very clear since the first moment that aerodynamics was just one of several elements of the Rail 52 design. When it came out, it was the first carbon clincher to have an 18mm bead seat width. Zipp had some in the 16 and change range, but we very specifically wanted 18. Crosswind stability was also critical, and it's proven to be a very effective part of the Rail 52 design. Speed for every element - cornering, handling, and aerodynamics. 

We went through the expensive and, I'll just take credit for it, the honesty of showing you what the actual aerodynamic gap was between popular aluminum wheels and shallower carbon wheels. EVERY TIME you've heard someone reference Kinlin XC279 versus Pacenti aerodynamics, that's a test WE did. Show me where some other company made that kind of investment to show that an attribute that people were ascribing to _*their own product*_ wasn't as beneficial as people were allowing themselves to believe. 

Helmet tests done with mannequins with the straps taped to the mannequin's head, and random taping techniques? Garbage. The chief engineer at A2 during our last test (who's since moved to Joe Gibbs racing), who has tested more people with more helmets than probably anyone else, says that unless you test a helmet on yourself with your own setup, just get one you like the looks and color of because helmets are totally specific to riders. 

There are real gains to be had, of course, absolutely. Every time we've tried to quantify it, we've clearly labeled every protocol/asterix/caveat/whatever. Skin suits can save time, but versus what will tell you how much. My objection is when an optimal skin suit is compared versus some badly fitting "club cut" kit, or worse still an unknown entity. If you compare all "worst" in aerodynamics to all "first" in aerodynamics, then you wind up with some incredible gap. But no one's thinking "hmm, should I use my steel bike, commuting helmet, 32 spoke box section wheels, and baggy jersey, or my aero bike, aero helmet, deep wheels and skin suit in today's tt?" It's a false dichotomy, and that false dichotomy is where realism takes its leave.


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## deviousalex (Aug 18, 2010)

Notvintage said:


> It is to 99.5% of anyone on this forum. If you're not a pro riding for food who cares really?


Assuming this study is accurate, 35 watts is huge at 25 mph. One of my local training rides averages 26-27mph with some 3-5 minute power climbs thrown in. 35 watts over that course is going from my 1 hour power to my 4 hour power. So yes, it matters to your average joe.


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## stevesbike (Jun 3, 2002)

November Dave said:


> Semantically, it's much more contradictory than ironic. And to say that we sell wheels on the basis of aerodynamic savings is only part of the picture. We sell one set of wheels that has a significant aerodynamics component - the Rail 52. When we launched that, we went to great pains to compare it to a relevant comparative choice, specifically the Zipp 404. We didn't go out and find the biggest punching dummy we could and show a huge yawning gap of time savings against it, as was overwhelmingly the convention at the time and is still a popular method. We also did the correct thing and made all comparisons in the same wind tunnel at the same time with the same tire (not tires, tire). There are plenty of charts out there that compare tests from different times, different tunnels, different protocols, etc. One company compares their wheels at tared values against runs that were done at a different time with the values left untared. At every step, we've tried to be as specific, transparent, and applicable as possible.
> 
> We've also been very very clear since the first moment that aerodynamics was just one of several elements of the Rail 52 design. When it came out, it was the first carbon clincher to have an 18mm bead seat width. Zipp had some in the 16 and change range, but we very specifically wanted 18. Crosswind stability was also critical, and it's proven to be a very effective part of the Rail 52 design. Speed for every element - cornering, handling, and aerodynamics.
> 
> ...


sure, helmets interact with heads, rider posture, etc. But wheels also have interaction effects, so even your thorough testing includes assumptions. For example, your benchmark against the 404 was done with 23mm Vittoria tires although the 404 was optimized around a 21mm tangente. Tom Anhalt (among others) has recently shown differences in tire choice, including some significant ones for Hed 6 depending on 2mm tire width differences, indicating that these interactions increase with rim depth. So, is it a representative comparison to benchmark the unoptimized Zipp wheel/tire against the Rail 52? I'd also add that I don't think using a 0-350 gram y-axis for plots is an optimal way to display results, since eyeballing it flattens differences among wheels, which could be replotted in a 0-200 range (as does zipp). The display of quantitative information is just as important as the data itself. 

FWIW, benchmarking worst vs. best isn't a false dichotomy. The choice of a benchmark is arbitrary - the purpose is to provide a comparative result. So long as the consumer knows what the benchmark is, they should be able to interpret the results for themselves. The potentially best sort of information for consumers is independent third-party testing - as in the original Velonews article.


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## November Dave (Dec 7, 2011)

stevesbike said:


> The potentially best sort of information for consumers is independent third-party testing - as in the original Velonews article.


 I'd agree with this without reservation, but while Velonews is a third-party, they aren't independent. I will say that I don't think that they modified the results at all in any respect, but some prominent manufacturers weren't included.

We know all about the effect tire size can have on aerodynamics. We tested it. We also tested the Zipp (and an Enve) with a GP4000sII - both in 23 and 25mm sizes. Our stated reason for doing so was to give a test using the tire that most people paying close attention to this kind of stuff were using - to some degree thanks to Tom's testing and also because it was shown to be a fast tire in testing (Josh Poertner - then of Zipp - is largely credited with having found that out and "founding" that as the standard). A consensus coalesced around using that tire. Given the VN test, we may see a new default tire. 

Nobody used the Zipp tire. The flavor for 21s had passed, and Tom had shown that it was a dog in rolling resistance. Why test something no one's going to use? But if you have a citation for the development of the 404 around that tire it would be great, because while I know I've read that, there seems to be some revisionist history around that point. 

Tires make a huge (I use that term in this instance both earnestly and hyperbolically) difference not only in rolling resistance but in aerodynamics as well. Flip said GP4000sII around so it's going the "wrong" direction and your results will be well outside the margin of error with it facing the "right" way. 

As for the presentation of data, it's there and you're free to rearrange it however you like. Your opinion on the best way to present that data is certainly valid, but I don't think even Professor Tufte would agree with the presentation being as important as the data. Zipp presents precious little data these days, and I can sympathize with their reasons for doing so. 

Last, to interactive effects, Dave Salazar (formerly of A2) was of the belief that fast wheels were generally fast wheels in whatever bike, and that a front wheel's standalone performance was an effective proxy for how that wheel would generally fare in a given bike, with or without a rider. His thought on helmets was that absent the user context, it was more or less random. The best helmet for you could be my worst. 

Again, simply, there's there there. Our intent has always been to present as clearly, honestly, and usefully as possible. I think the evidence is inarguable that we've made that intent. But I've heard 1 hour 40k people say that with some better choices they can go 53'. I don't think anyone's doing that with a credit card.


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## burkeqc (Sep 25, 2006)

Thank you for showing the Bike Calculator link, which I have used for several years to make comparisons. Tire rolling resistance tests are all different, so it pays to carefully read how the test was done.


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## ergott (Feb 26, 2006)

stevesbike said:


> unoptimized Zipp wheel/tire against the Rail 52?


What good is an optimized combo (21mm Tangente and Zipp 404) when I doubt many people even use that tire? The Vittoria tires are more representative of what riders use.


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## ibericb (Oct 28, 2014)

burkeqc said:


> Thank you for showing the Bike Calculator link, which I have used for several years to make comparisons. Tire rolling resistance tests are all different, so it pays to carefully read how the test was done.


Bike Calculator is a simple to use calculator that allows for simple comparisons. It is a useful tool, but one with significant limitations. If ever you want to get more rigorous, try Analytic Cycling. Just be prepared to have all the necessary parameters.


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## BikeLayne (Apr 4, 2014)

ziscwg said:


> If you get your watt saving tires and I pass your a$$ on the climb like you're standing still, did you get your moneys worth?
> 
> Sometime we over analyze all these numbers and device that are better. Yet, we don't look in the mirror and try to figure out how to improve what we see.


Probably as I needed tires and am glad to have them. If somebody passes me then I say "good morning".


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## Z'mer (Oct 28, 2013)

dcgriz said:


> Tour magazine did a rolling resistance test on a bunch of popular tires back in the spring of 2014. See how the results vary from the VN test.
> http://www.conti-tyres.co.uk/contic...Tests/Wide_Tyre_Test_TourMagazine_2014_UK.pdf
> Tour also indicated that testing the tires on rollers tends to exaggerate the resistance values. According to them testing the tires on a flatter surface, like a belt, gives more accurate results. Their test shows the difference between the Conti 4ksii and the Michelin Pro Comp is not more than a few watts.


Thanks for posting that link. From the recent VN article on rolling resistance, people would think the hot new tire is the line from Specialized S Works.

But reading this review above, they say the S Works tire basically flunks the puncture test. 
That raises a big red flag for using it everyday for fast training.


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## dcgriz (Feb 13, 2011)

Z'mer said:


> Thanks for posting that link. From the recent VN article on rolling resistance, people would think the hot new tire is the line from Specialized S Works.
> 
> But reading this review above, they say the S Works tire basically flunks the puncture test.
> That raises a big red flag for using it everyday for fast training.


You are quite welcome. The S-Works is a fast tire; no doubt about that. However, whether or not is the best fit for one's predicament its more involve than just picking a Crr number, no matter whose Crr you pick. I believe the plethora of data available is both good and bad. Good from the point of having multiple results to analyze and bad if you indiscriminately pick the "no. 1" contestant looking for a quick fix.

Here is another test
Blather 'bout Bikes: Win Tunnel Playtime - Part 1
this one in Specialized's wind tunnel and with some tubes thrown in the mix (click on the rolling resistance table on the upper right)


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## dcb (Jul 21, 2008)

dcgriz said:


> Here is another test
> Blather 'bout Bikes: Win Tunnel Playtime - Part 1
> this one in Specialized's wind tunnel and with some tubes thrown in the mix (click on the rolling resistance table on the upper right)


Thanks for both of those links they are very interesting. It seems like this type of information could be used to make some educated guesses about which tire/rim combo might be best for certain races, or just chasing Strava segments if you're into that sort of thing. Maybe it would look something like this:

- wide tire with low crr for a race/ride in which a particular climb or climbs that are steep enough to negate any aero benefit of a narrow tire.

- narrow tire for a flatter race/ride especially if it's windy.

I'm assuming the aero tests were done with a standalone wheel or as the front wheel on the bike. I wonder how much of an aero difference there is between say a 23 and 28mm conti when it's mounted to the rear wheel?


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## November Dave (Dec 7, 2011)

Rear wheel aerodynamics are worth about half of what they are in the front. So if you interpolate between this test and this test, the penalty for going from a "23" that's actually closer to 25-ish and a "25" that's closer to 27-ish, you're giving up about 5 seconds in the mythical wind tunnel 40k TT. 

Wider tires (in front in particular) also degrade crosswind stability. 

Any excuse to link to that Brochard picture, I take. Best. Mullet. Ever.


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## Jay Strongbow (May 8, 2010)

November Dave said:


> Any excuse to link to that Brochard picture, I take. Best. Mullet. Ever.


I played *hockey* in the mid/late *80's and early 90's* with many games and tourneys in *Canada*.
In other words I have serious credentials in this area and I can not dispute your ranking of that mullet.


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## stevesbike (Jun 3, 2002)

ergott said:


> What good is an optimized combo (21mm Tangente and Zipp 404) when I doubt many people even use that tire? The Vittoria tires are more representative of what riders use.


Seriously? Just go to slowtwitch to see how much people agonize/research equipment choices. It's just dumb to spend $2k on a wheelset and not spend a few minutes figuring out which tires are beset for it. Zipp puts it right in their FAQ re tire choice and blogs like Anhalt's help with additional data (upcoming) optimizing via both Crr and aero data.


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## Notvintage (May 19, 2013)

deviousalex said:


> . 35 watts over that course is going from my 1 hour power to my 4 hour power. So yes, it matters to your average joe.


Yes, but how did that improve your life/cycling experience? Did you win money or something? Go from CAT 1 to Pro?


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## stevesbike (Jun 3, 2002)

Notvintage said:


> Yes, but how did that improve your life/cycling experience? Did you win money or something? Go from CAT 1 to Pro?


if you compete and put in the hours required to be competitive while managing a full-time job, family obligations, etc. then having good equipment and investing time in equipment selection - at the very least - helps remaining committed. It's motivating. The same holds true for many people who ride for fitness rather than competition. In terms of competition, there's no doubt that these choices often influence placing in races, where a few seconds often separate finishers. If I'm going to spend 15+ hours a week training, spending money on traveling etc. to race a time trial, I don't want to show up at the start line knowing I'm giving up a minute to some other competitors due to equipment....


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## November Dave (Dec 7, 2011)

While I personally break out in a rash when someone mentions the words "time trial," I completely agree with this sentiment. Getting fit and arranging your life to get to the line with a chance at a good ride is, except for the exceptional few, the biggest investment of all. The different elements of road racing will often mitigate equipment selection choices - quite good is necessary, but quite good is almost always good enough. Time trials are a very very different animal.


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## deviousalex (Aug 18, 2010)

Notvintage said:


> Yes, but how did that improve your life/cycling experience? Did you win money or something? Go from CAT 1 to Pro?


Why is it that everyone on this forum is of the opinion that if you aren't going Cat1 to Pro it does't matter? As I stated it was a group ride. And while I haven't ridden faster tires yet (I'm using near bottom of that list Michelin Lithion 2s) the first time I didn't get dropped on that ride (the spot where most people usually get dropped is 50 miles from my house so if you're dropped it's a long solo ride home) it felt like I had achieved something great. Being able to keep up with some of the fastest racers out in the area was a great experience for me and at the end of that ride I felt like I had accomplished something.

If I have the disposable income why not ride better equipment? I've started to realize this. I've saved up enough cash to the point where I realize I might as well spend it while I'm young. I like to think I find the balance between performance and price. I bought Ultegra Di2 instead of Dura Ace Di2 for my new ride because I know that the weight difference isn't huge in the grand scheme of things. I bought a high quality frameset at a closeout price because I know getting a $5k frame is generally not worth it over the comparable $3k frame.

The ride quality of some good tires outweighs the disadvantages. When I put on my race wheelset (only during races, so about 3-5% of my total mileage) I can't help but notice how much smoother the ride is. I am starting to change my mind about riding crappy tires. What really threw me off good tires is when I buy one and get an unfortunate extreme puncture that just ruins the tire. This happened two times in two months (with an S-Works tire and a GP4000S tire), not to the tire's own fault, but rather running over something like an industrial sized nail at night. But with being able to get something decent at a good price these days online or via team sponsorship my view is starting to change.

For the TL;DR - Why do a lot of people on this forum think good stuff only matters to pros? If I have the disposable income and buying nice tires makes me happy, why not go for it? Money can buy happiness to a certain point.

Can Money Buy Happiness? Here?s What Science Has to Say - WSJ


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## Jay Strongbow (May 8, 2010)

Notvintage said:


> Yes, but how did that improve your life/cycling experience? Did you win money or something? Go from CAT 1 to Pro?


Well if improving one's life is the criteria for doing something I'm curious how taking the time to post that question on the internet has improved yours?


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## deviousalex (Aug 18, 2010)

Jay Strongbow said:


> Well if improving one's life is the criteria for doing something I'm curious how taking the time to post that question on the internet has improved yours?


Exaaaaactly. I'd give you rep but I have to spread some of the lovin around before I can.

I'm curious to see what Notvintage's bike looks like. But since it's the internet he could post a wal-mart beater and claim he rides at 5W/kg on gatorskins with extra anti-puncture belts put in them.


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## dcgriz (Feb 13, 2011)

dcb said:


> Thanks for both of those links they are very interesting. It seems like this type of information could be used to make some educated guesses about which tire/rim combo might be best for certain races, or just chasing Strava segments if you're into that sort of thing. Maybe it would look something like this:
> 
> - wide tire with low crr for a race/ride in which a particular climb or climbs that are steep enough to negate any aero benefit of a narrow tire.
> 
> ...


As Novemner Dave allready replied, the back wheel is the back wheel. Too much is happening back there to worry too much about it.

The race guys who pedal for a living call for wide tires and rock hard pressures to squeeze any watt or fraction of watt out of them.
https://m.youtube.com/watch?v=2pIHm40Amx0 I would think they also optimize the crossectional profile of the rim/tire.

I believe latex tubes would do more for you if you race on clinchers than any of the wide tire - narrow tire iterations you indicated. Something in the 5-8 watts range if I recall correctly.


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## robt57 (Jul 23, 2011)

dcgriz said:


> I believe latex tubes would do more for you if you race on clinchers than any of the wide tire - narrow tire iterations you indicated. Something in the 5-8 watts range if I recall correctly.


I seem to recall seeing one of the CRR charts showing the GP4K way down with latex tube...


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## ibericb (Oct 28, 2014)

robt57 said:


> I seem to recall seeing one of the CRR charts showing the GP4K way down with latex tube...


If you believe the Bike Tire Rolling Resistance numbers, you can see comparisons done with latex vs butyl tubes here. From that dataset, GP 4000sII @ 100 psi 11.1 W vs. 12.9 W, 1.8 W difference; Vittoria Open Corsa CX III 12.2 W vs 13.6 W, 1.4 W difference. There's also this more comprehensive test of Schwalbe One tubeless vs. latex, light and standard butyl tubes. Bear in mind the test conditions. The results seem to be consistent with ~ 10-15% improvement in rolling resistance.


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## dcgriz (Feb 13, 2011)

10-15% reduction in rolling resistance is a good approximation. Morrison's tests suggest even higher improvement with supple tires
Butyl v Latex | CyclingTips

Latex tubes are the lowest $/watt in the pursuit of watts other than pumping more air into your tires. Better puncture protection is the bonus.


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## ibericb (Oct 28, 2014)

dcgriz said:


> 10-15% reduction in rolling resistance is a good approximation. Morrison's tests suggest even higher improvement with supple tires
> Butyl v Latex | CyclingTips
> 
> Latex tubes are the lowest $/watt in the pursuit of watts other than pumping more air into your tires. Better puncture protection is the bonus.


You can get the actual data from Morrison's last tests here. Scroll down to page 4, and see the section section for latex vs. butyl for the three different tires. The average difference is 11.4%, the largest is ~ 15.7%, the smallest is ~3.9%. So with good quality tires you'd save ~ 4 watts for the set at speed (Morrison's tests were done at 51 km/h, but his power numbers are presented for 25 mph with a 100 lb load on the tire), average savings of that set per Morrison was 1.9 W/tire.


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## dcgriz (Feb 13, 2011)

ibericb said:


> You can get the actual data from Morrison's last tests here. Scroll down to page 4, and see the section section for latex vs. butyl for the three different tires. The average difference is 11.4%, the largest is ~ 15.7%, the smallest is ~3.9%. So with good quality tires you'd save ~ 4 watts for the set at speed (Morrison's tests were done at 51 km/h, but his power numbers are presented for 25 mph with a 100 lb load on the tire), average savings of that set per Morrison was 1.9 W/tire.


Yes, I'm aware of the pdf. Notice how the difference in rolling resistance between butyl and latex on the same tire is exaggerated when a supple tire is tested vs. a stiffer tire.
Veloflex Pave drops from 18.5 w to 15.7 w and Vittoria Evo CX from 15.1 w to 12.8 w while the Schwalbe only spans between 16.5 w and 15.8 w and the Michelin fares similarly.
This suggests to me that the extra effort associated with the use of latex pays greater dividends when supple tires are used rather than tires with stiffer casings. Personally, my choices of tires to use with latex tubes are from open tubulars.


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## ibericb (Oct 28, 2014)

It seems to me that all the tests we've seen (Morrison, and bike tire rr site) are too limited to draw any major conclusions or trends, other than latex is lower than butyl for Crr as tested in the lab. As Morrison notes his tests were done on a smooth drum (the RR site uses a diamond tread plate, as do the Fins), and on actual road surfaces the difference could be 100%. Will latex then have a greater proportional effect, or will it be about the same, or less? From what little data I've seen we don't really know.


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## dcgriz (Feb 13, 2011)

I have been arguing against using these Crr values in vacuum all along so I totally concur with the stipulation that there is a lot of maneuvering within the data available on the subject of rolling resistance.
I do agree that a sample population of 8 is extremely small to derive statistical data representing tires in general although meaningful enough to possibly able to indicate the direction the symptom may follow. Would be nice to have more tests done on the subject.
For the folks who happen to use the tested tires in the first place, the decision to use or not use latex tubes is much simpler to make. Definitely helped me make up my mind on the subject.


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## daronl (Apr 1, 2012)

The GP4000s II are my all time favorite tires. I won't ride any other tire.


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