# Directional tread on tires?



## tarwheel2 (Jul 7, 2005)

I installed some Panaracer TGs on my commuter bike a couple of weeks ago but removed them after two days because my bike felt so much slower. Actually, it wasn't just a feeling -- my average speed those two days was about 2 mph slower than usual.

I got to looking at the Panaracers over the weekend and realized that they have a directional arrow on the sidewalls. They actually are supposed to be mounted with the tread facing a certain direction -- the opposite of how I had installed them. I always install my tires so the decal lines up with the valve on the quick release side of my bike, so I can more easily locate holes in tubes when I get a flat. Turns out that the tread was facing backwards when I mounted the tires my usual way.

I've never used bike tires before than had directional treads. Is this common? I've always used Michelins and other tires without much tread and no directional requirements. BTW, my bike definitely rolled a lot smoother and faster with the tires turned the right way.


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## Mark McM (Jun 18, 2005)

*Tread patterns are non-directional because they are also non-functional*



tarwheel2 said:


> I've never used bike tires before than had directional treads. Is this common? I've always used Michelins and other tires without much tread and no directional requirements. BTW, my bike definitely rolled a lot smoother and faster with the tires turned the right way.


Tread patterns on bicycle tires meant for pavement are primarily cosmetic. Unlike relatively wide, low pressure tires found on motor vehicles, the narrow high pressure tires found on bicycles can not hydroplane (well, at least not at speeds you are ever likely to see on a bike), and therefore the tread patterns on bicycle tires serve no function. Therefore, bicycle treads are not directional.


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## Pelon2 (Dec 25, 2005)

*Not directional*

:confused5: Most higher end bycle tires are directional and there are a variety of tread patterns and rubber compounds for different road surfaces and weather conditions.
As for hydroplaneing,no but slideout due to wet road,ice patch or loose road surface is 
where tread,compound and direction of rotation do make a difference.
This of cource is just my 2cents take it or leave it.


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## tarwheel2 (Jul 7, 2005)

All I can say is the sidewalls of my Pasellas say to mount them facing a certain direction. When I inadvertently mounted them the opposite way, they had significantly more rolling resistance. I notice the resistance without even realizing the tires were mounted wrong.

I always used Michelins and other brands with no tread patterns, so I never encountered this issue before. For instance, there is no right or wrong way to mount a Michelin ProRace with regard to the tread because they have no tread pattern. The Paselas, in contrast, do have a tread pattern.


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## Kerry Irons (Feb 25, 2002)

*Leavit*



Pelon2 said:


> :confused5: Most higher end bycle tires are directional and there are a variety of tread patterns and rubber compounds for different road surfaces and weather conditions.
> As for hydroplaneing,no but slideout due to wet road,ice patch or loose road surface is
> where tread,compound and direction of rotation do make a difference.
> This of cource is just my 2cents take it or leave it.


Hmmm. Take it. Or leave it. Hmmmm. Well, since it is based on no data and no engineering principles, I guess I will vote for "leave it." Modern road tires do NOT change ride characteristics in any way because of mounting direction. Deep cut tread? Sure. But those aren't what we're talking about here.


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## rdolson (Sep 2, 2003)

Tradition is to have the tire label on the drive side of the bike, on the opposite side of the rim from the valve hole. But with some modern tires having multiple labels on both sides of the tire...


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## wim (Feb 28, 2005)

> Tradition is to have the tire label on the drive side of the bike, on the opposite side of the rim from the valve hole


Must be a new tradition. The old tradition was to have the tire label(s) centered over the valve. Gosh durn, nothin ever stays the same any more . . .


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## Sixty Fiver (Jul 7, 2007)

The Pasela is a touring tire with a deeper tread that is designed to roll better when it's installed with a proper orientation.

Many tires are direction specific and when you get into off road tires you also get front / rear specific tires that optimize traction and handling.


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## Sixty Fiver (Jul 7, 2007)

My tire labels are centered over the valve hole... I guess I'm a luddite.


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## rdolson (Sep 2, 2003)

Take a look at a set of tubulars, tire labes are opposite the valve, have been for as long as I've used em (over 25yrs). Clinchers if you care to follow with that, go ahead, just keep the label on the drive side of the bike.


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## Sixty Fiver (Jul 7, 2007)

The Schwalbes I just out on my Rocky are directional so it's impossible to have the label on the rear tire facing the drive side unless you mount it backwards.


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## Mark McM (Jun 18, 2005)

*Bicycle tire tread is non-functional, and therefore inherently non-directional*



tarwheel2 said:


> All I can say is the sidewalls of my Pasellas say to mount them facing a certain direction. When I inadvertently mounted them the opposite way, they had significantly more rolling resistance. I notice the resistance without even realizing the tires were mounted wrong.


There was either something else going on, or you were imagining things. Tread patterns on narrow road tires is too shallow to have any significant affect, let alone have some kind of directional affect.

Tread patterns are put on bicycle tires for cosmetic and marketing reasons, not performance reasons. Many consumers see that automobile tires have tread, and therefore make the assumption that bicycle tires should too. These consumers then shy away from smooth treaded road tires, assuming that these "bald" tires have poor traction, and instead want to buy tires with a tread pattern. Thus, in order to stay in business, tire manucturers make what the consumers want - regardless of whether it really is a better product.

Motorized racers have long figured out that on dry pavement, smooth treaded tires always have better traction and lower rolling resistance. That is why all dry road racing tires (stock cars, sports cars, formula 1, Indy cars, dragsters, etc.) use smooth tires. Similarly, bicycles also perform best on smooth treaded tires. 

On wet roads, the wide, low pressure tires used on motor vehicles tend to hydroplane, so grooves and sipes are added to prevent hydroplaning. But because bicycle tires are much narrower and under higher pressure, the speeds at which they can hydroplane are much higher than for motor vehicles. Even for wet roads, smooth treaded bicycle tires perform better. (Also notice that the contact patch of a bicycle tire is smaller than a single tread block of a grooved and siped motor vehicle tire).

Because tread pattern on a bicycle tire is non-functional, they are inherently non-directional.


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## acid_rider (Nov 23, 2004)

*Gp4000*

my GP4000 tyres have arrows on sidewalls indicating they are directional even though they practically have no tread. 

I send e-mail to Conti with a question and (surprise) heard nothing back from them.

There must be a reason for those arrows, beyond pure marketing. 

I *think* the internal fibres/threads/etc are laid out internally in certain way/direction as to influence tyre handling/cornering/wet-road behaviour. I dont this rollling on a straight and dry road you will notice any difference if they are mounted "incorrectly" wrt directional arrows.


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## Mark McM (Jun 18, 2005)

*Why should a slick tire be directional?*



acid_rider said:


> my GP4000 tyres have arrows on sidewalls indicating they are directional even though they practically have no tread.
> 
> I send e-mail to Conti with a question and (surprise) heard nothing back from them.
> 
> ...


Are you just speculating about the casing threads making the casing directional? Why should bicycle tires be directional, when no other slick tires (automobile, motorcycle, airplane etc.) are directional? It is even questionable about whether some tires with deeply patterned treads are at all directional. Motocross tires used to be made with assymmetrical (directional treads), but they are no longer made this way, primarily because they figured out it served no function. And if deeply knobbed tires made for very soft conditions aren't directional, why should slick treads made for hard surfaces be directional.

Directional arrows are placed on road bike tires for the same reason that patterned treads are - to enhance their perceived value (but not their actual performance).


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## acid_rider (Nov 23, 2004)

*yes*



Mark McM said:


> Are you just speculating about the casing threads making the casing directional?
> Directional arrows are placed on road bike tires for the same reason that patterned treads are - to enhance their perceived value (but not their actual performance).


I agree, yes, we are *both* speculating here. I have yet to hear anything official from Continental, after 1 week since my question was e-mailed to them. They clearly do care about their customer questions! NOT! 

I dont think having directional arrows on tyres enhances anything. There is a tiny bit of side-wall tread on GP4000 so perhaps this is the reason for arrows. Or total BS. 8^)


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## Mark McM (Jun 18, 2005)

acid_rider said:


> I agree, yes, we are *both* speculating here.


I'm not so sure about that. There is no speculation that all bicycle tires use 45 degree bias plies, and that they are rotationally symmetric (non-directional). There is also no speculation that the tread does not penetrate the pavement, and that the tire at the contact point is essentially stationary (i.e. the bottom of the wheel is not moving forward with the respect to the ground.


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## asgelle (Apr 21, 2003)

Mark McM said:


> Why should bicycle tires be directional, when no other slick tires (automobile, motorcycle, airplane etc.) are directional?


F1 tires (grooved slicks) are directional through the casing construction.


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## Fivethumbs (Jul 26, 2005)

I watched a documentary on legendary motorcycle road racing champion Kenny Roberts. He raced in the States on slicks as they did not race in the rain in the U.S.. Once he was racing in Europe and it started to rain. To Kenny's surprise the race was not cancelled. He had no motorcycle tires with treads. He asked the other teams if he could borrow a set of rain tires (with grooves/treads); however, no team would lend him tires. He was able to get ahold of a tread cutter and cut his own treads in his slicks and won the race. I know bicycle tires aren't quite the same as motorcycle tires but they seem fairly similar. One would think that if you need motorcycle tires with treads to ride/race in the wet, then you would need the same for bicycle tires, as 50-60 mph downhills in cycling is not uncommon. As far as tread pattern goes, I thought the idea was to channel any water away from the center of the tire. If you flipped the tire around it would channel the water toward the center of the tire.


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## Kerry Irons (Feb 25, 2002)

*Hydroplaning*



Fivethumbs said:


> One would think that if you need motorcycle tires with treads to ride/race in the wet, then you would need the same for bicycle tires, as 50-60 mph downhills in cycling is not uncommon.


Bicycle tires require nearly 100 mph to hydroplane, given the high pressure. Motocycle tires have much lower pressure and will, therefore, hydroplane at much lower speeds. Knowing these facts is the difference between what "one would think" and reality


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## Fivethumbs (Jul 26, 2005)

Are you saying that at speeds less than 100 mph a slick bicycle tire offers the exact same traction as a grooved bicycle tire in the wet? I have no experience other than a typical layman's but that doesn't sound right to me.


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## Forrest Root (Dec 22, 2006)

Fivethumbs said:


> Are you saying that at speeds less than 100 mph a slick bicycle tire offers the exact same traction as a grooved bicycle tire in the wet? I have no experience other than a typical layman's but that doesn't sound right to me.


Yup. That's what he's saying, and that's what is true. It's a fact, no matter what you think.

Also, the Continental "directional arrow" is not there for any important reason. Hell, Dunlop got an intermediate rain tire for GP motorcycles approved by the DOT so they could use it in supersport motorcycle racing, here in the US, where tires had to be DOT tires. And, it so happened that some folks chose to run the front tires, on those tire sets, counter to their directional arrow. And they wuz going a lot faster than anyone here will go on their bikes.


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## Fivethumbs (Jul 26, 2005)

I was skeptical but I found something that backs up what you say.

_"Benefits of smooth tread are not easily demonstrated because most
bicycle riders seldom ride near the limit of traction in either curves
or braking. There is no simple measure of elapsed time or lean angle
that clearly demonstrates any advantage, partly because skill among
riders varies greatly. However, machines that measure traction show
that smooth tires corner better on both wet and dry pavement. In such
tests, other things being equal, smooth tires achieve greater lean
angles while having lower rolling resistance.

Tread patterns have no effect on surfaces in which they leave no
impression. That is to say, if the road is harder than the tire, a
tread pattern does not improve traction. That smooth tires have
better dry traction is probably accepted by most bicyclists, but wet
pavement still appears to raise doubts even though motorcycles have
shown that tread patterns do not improve wet traction.

A window-cleaning squeegee demonstrates this effect well. Even with a
new sharp edge, it glides effortlessly over wet glass leaving a
microscopic layer of water behind to evaporate. On a second swipe,
the squeegee sticks to the dry glass. This example should make
apparent that the lubricating water layer cannot be removed by tire
tread, and that only the micro-grit of the road surface can penetrate
this layer to give traction. For this reason, metal plates, paint
stripes, and railway tracks are incorrigibly slippery.

Besides having better wet and dry traction, smooth tread also has
lower rolling resistance, because its rubber does not deform into
tread voids. Rubber being essentially incompressible, deforms like a
water filled balloon, changing shape, but not volume. For a tire with
tread voids, its rubber bulges under load and rebounds with less force
than the deforming force. This internal damping causes the energy
losses of rolling resistance. In contrast the smooth tread transmits
the load to the loss-free pneumatic compliance of the tire.

In curves, tread features squirm to allow walking and ultimately,
early breakout. This is best demonstrated on knobby MTB tires, some
of which track so poorly that they are difficult to ride no-hands.

Although knobby wheelbarrow tires serves only to trap dirt, smooth
tires may yet be accepted there sooner than for bicycles."_


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## Sixty Fiver (Jul 7, 2007)

_Tread patterns have no effect on surfaces in which they leave no
impression. That is to say, if the road is harder than the tire, a
tread pattern does not improve traction. _

That is fine for road bikes but for mountain bikes and motorcycles the type of rubber compounds used, the characteristics of the tyre, and the tread make a huge difference in how the machine performs.

I rode a motorcycle for many years and did find a marked improvement in wet performance when I set my bike up with Avon Super Venoms which are / were regarded as one of the best wet performance tires. In riding through torrential rains the bike handled nearly as well as it did on dry pavement whereas other tires I ran felt sketchy at speed in the rain.

I just changed the tyres on my mb from aggressive knobbies to much slicker offroad tyres and on the hardpacked trails I ride the slicker tyres roll faster and actually climb better than the tires that look like they should be able to climb walls. When it gets wet I have another mb set up with tyres better suited for muddy conditions.

The most telling thing about slick tyres and their traction abilities is that many fixed gear riders here run the same slicks in the winter as they do in the summer and we get a good share of snow and ice.


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## al0 (Jan 24, 2003)

Compounds - yes, theymake difference (but not always intended by manufacturer), threads - pure cosmetic.

BTW, it was shown by tests (German TOUR magazine) that "wet-road" tires serve on wet roads by no means better then general-purpose tires.



Pelon2 said:


> :confused5: Most higher end bycle tires are directional and there are a variety of tread patterns and rubber compounds for different road surfaces and weather conditions.
> As for hydroplaneing,no but slideout due to wet road,ice patch or loose road surface is
> where tread,compound and direction of rotation do make a difference.
> This of cource is just my 2cents take it or leave it.


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## asgelle (Apr 21, 2003)

Fivethumbs said:


> I was skeptical but I found something that backs up what you say.



Of course, without the source or a link, there's no way of knowing whether this author has any more of a clue than others here. All I can tell is he (she?) tells a pretty story.


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## mh3 (Mar 8, 2006)

For the piece fivethumbs listed, I believe the author is Jobst Brandt. Whether he has a clue or not depends on your feelings about engineers in general I suppose, but his credentials are more then credible. He's also the author of "the bicycle wheel". 

I don't have the exact link handy, but the piece can be found  here in the index. Hmmm, might be  this one. There's also a bunch of his stuff on Sheldon Browns site.

Cheers


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## asgelle (Apr 21, 2003)

mh3 said:


> For the piece fivethumbs listed, I believe the author is Jobst Brandt.


That's not the point. The reference should have been included in the original post. Otherwise, for all we know, fivethumbs could have written it himself, but credited it to some other authority to make it seem more credible.


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## MikeBiker (Mar 9, 2003)

If treads provided traction, then automotive race tires would have nice threads. They don't.


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## mh3 (Mar 8, 2006)

asgelle said:


> That's not the point. The reference should have been included in the original post. Otherwise, for all we know, fivethumbs could have written it himself, but credited it to some other authority to make it seem more credible.


Agreed.

I suppose I could have asked him to verify what he'd written, but it was easier for me to do a google search. I decided in the interest of moving the discussion forward, it would be more informative to provide a link to the source he cited rather than point out he made a procedural error. That's the point.

Cheers.


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## rdolson (Sep 2, 2003)

*Too much traction?*

Ok, I will go along with the slick being superior in delivering traction on a firm dry surface. But my only experiance (Other than my Schwinn Sting Ray 5sp Stick in 1966) on road slicks was the Specialized Cipolini kevlar clincher about 4 years ago. It was louder, esp. in out of the saddle sprints, than the Evo CX's. I also felt slower on them. The slick actually felt superior in wet conditions, with a more solid, predictable feel that was more confidence inspiring when hitting a rough patch descending in the wet.

I wonder if the treads have any effect in the wind tunnel? Does a treadded tire have better airflow management, even if it was only miniscule, when mounted in a certain direction?

Fuel for the fire...


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## Cory (Jan 29, 2004)

*I know the answer to this. No, really. In theory, anyway.*

A retired car-tire engineer buddy of mine got interested in cycling about 10 years ago and spent five or six years testing and developing equipment, including a pneumatic shifting system that worked great, but he gave up on it because existing shifters already work great and weigh less. He'd done a couple of decades designing racing tires for 200mph cars, and he used to sneer at the arguments over bike tires, as well as other debates like Campy tools vs. Park {"Buy Campy if you like the feel in your hand, but a $2 socket set is fine for the stresses involved in working on a bicycle").
For awhile he was interested in bike tires, but gave it up: Too easy to be interesting. His claims about tires (which I'm not defending, just passing along) included insisting that tread doesn't matter except maybe in snow. The rubber compound makes a difference, and the amount of rubber in contact with the pavement counts. On a treaded tire there's less of it--you don't get any traction from the voids in the tread pattern. He rode Avocet slicks in all conditions.
As for the Panaracers, I've used them exclusively for about five years on both my road bikes, and I can't tell a difference depending on which way they're mounted. I doubt there is one, but I'm not committed to that. I'm pretty slow no matter which way they're facing, and maybe a faster, more consistent rider could feel a difference.
When I mount them, though, I mount them so that theoretical water, encountering the theoretically useless tread, will be forced back and away from the centerline of the tire rather than being channeled toward it. That's the way car tires are designed, and even though Don swore it didn't make a difference on bikes, what can it hurt?


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## Mark McM (Jun 18, 2005)

*Directional F1 tires reference?*



asgelle said:


> F1 tires (grooved slicks) are directional through the casing construction.


Have you got a reference for this? The only information I could find on directional racing tires was directional tread grooves/siping for water displacement on wet roads (which we already know aren't required for bicycle tires).

Also, as you probably know, the reason for the grooved treads on F1 dry pavement tires is to _reduce_ traction (anothere way to limit speeds for safety on the racetrack).


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## asgelle (Apr 21, 2003)

Mark McM said:


> Have you got a reference for this? The only information I could find on directional racing tires was directional tread grooves/siping for water displacement on wet roads (which we already know aren't required for bicycle tires).


Steve Matchett mentioned it during some recent F1 coverage.


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## danl1 (Jul 23, 2005)

Our local self-appointed band of experts here are mostly right, but they are missing one critical point that you may stumble upon by accident in mounting the tyres the way you do: The direction a treaded tyre is mounted can make a difference, where there is a directional asymmetry.

Regarding hydroplaning and water siping, our pundits are correct: tread doesn't help, and by reducing available contact area, can actually hurt. But that's not the whole story, unless you regularly ride upon steel drums or glass sheets.

If riding on asphalt, concrete, and other 'real' road conditions, tread can, in some instances, help. The reason? It increases mechanical contact, or 'bite' with the road, the 'tooth' on the tyre interfacing with the surface of the road. 

As a simple example, look at the tread on a Michelin Transworld City. It could be mounted such that either the outside or inside of the sipe contacted the road first. Mounting that tire such that the inside contacted first would also allow the best 'edging' of that sipe with whatever road surface was available, as compared with the other way around, which would do little except decrease the available contact surface. A slick would do better all around, but once a bad decision has been made, one may as well limit the damage. 

And relevant to the OP's concern, while I tend to doubt that it's very noticable, one direction or the other (on dry pavement) could change the way the tire scrubs as the contact patch is established as the wheel rolls, and so affect rolling resistance. I don't know that it's the case with any particular road bike tyre, but a Pasela could conceivably exhibit that sort of behaviour.


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## asgelle (Apr 21, 2003)

danl1 said:


> other 'real' road conditions, tread can, in some instances, help. The reason? It increases mechanical contact, or 'bite' with the road, the 'tooth' on the tyre interfacing with the surface of the road.


Care to expand on how air in place of rubber increases mechanical contact? Brandt explains pretty well how asperities in the road are responsible for breaking through the lubrication layer.


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## Fivethumbs (Jul 26, 2005)

It was snipped from Jobst Brandt's blog.


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## Mark McM (Jun 18, 2005)

*Rubber does not "bite" into asphalt*



danl1 said:


> Our local self-appointed band of experts here are mostly right, but they are missing one critical point that you may stumble upon by accident in mounting the tyres the way you do: The direction a treaded tyre is mounted can make a difference, where there is a directional asymmetry.


Uh, oh, it looks we have another self-appointed expert here.



danl1 said:


> If riding on asphalt, concrete, and other 'real' road conditions, tread can, in some instances, help. The reason? It increases mechanical contact, or 'bite' with the road, the 'tooth' on the tyre interfacing with the surface of the road.


It looks like our "self-appointed expert" is going off the deep end. Tires do not "bite" into pavement - rubber is far to soft compared to asphalt for there to be any traction associated with "biting". Traction is from the interaction along the surface area of contact - and sipes (or other patterned tread features) only serve to reduce contact area.


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## danl1 (Jul 23, 2005)

Run two knife blades against one another. Then run two hacksaw blades against one another. 

Let me know which one moves most smoothly. 

OR, Slide a newspaper across the driveway, then try the same with sandpaper. 

Friends, there's more to traction than friction.

It matters not (to this portion of the discussion) how soft the rubber is, what matters is the shape of that rubber. 'Bite' isn't about displacing any asphalt - anyone hallucinatory enough to even imagine that was being suggested needs to step away from the hash pipe. In this context, 'bite' is about one object's edges interfacing with the edges on another surface. Turns out, in the 3D world, things aren't perfectly smooth or flat, and have corners and edges which can interfere with one another's passing. 


For those challenged by reading for comprehension, I will repeat what I said - that all else equal, a slick will provide optimum traction on a bicycle tyre, and is the best choice. *HOWEVER,* given that a tread is being used, the direction in which it is mounted can indeed matter. 

I offer the following gedankenexperimente. Into your tire, we will cut a series of grooves, spaced equally. You may include or ignore effects of differential casing flexibility at your choice. Assuming the rubber thick enough to take the abuse, it is your position that you have no preference if we cut them either longitudinally or laterally. After all, either direction will decrease the surface area equally, and will make no difference to either handling or rolling resistance, as compared to one another.

Thanks for playing.


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## asgelle (Apr 21, 2003)

danl1 said:


> It matters not (to this portion of the discussion) how soft the rubber is, what matters is the shape of that rubber.


Repetition does not constitute proof. It's notable that all your examples are for hard materials that do not deform under load as rubber does.


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## Fivethumbs (Jul 26, 2005)

A wise old gentleman told me once, "Believe half of what you read and none of what you hear." So keeping that in mind, I'm going to believe half of this thread....now all I have to do is figure out which half.


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## al0 (Jan 24, 2003)

danl1 said:


> ... 'Bite' isn't about displacing any asphalt - anyone hallucinatory enough to even imagine that was being suggested needs to step away from the hash pipe...


You need not hallucination to imagine or even observe this effect - in high summer it is typical enough, when asphalt is melting down under hot sun


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## critchie (Apr 27, 2004)

To many psots to read through, so here we go. It is not really about the tread, rather the layup of the threads of the tire. Yes, they are directional. 

Put the label at the value -- soley to identify where the flat occurred, nothing more. Or put them opposite, it's all the same.

Get your tires without tread -- it doesn't help the contact patch on 700/23 tires is too small to accually sipe any water.


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## Mark McM (Jun 18, 2005)

*Flying further off the deep end*



danl1 said:


> Run two knife blades against one another. Then run two hacksaw blades against one another.
> 
> Let me know which one moves most smoothly.


This is red hearring, which has no bearing on tire traction on pavement.



danl1 said:


> OR, Slide a newspaper across the driveway, then try the same with sandpaper.


Another red herring.



danl1 said:


> It matters not (to this portion of the discussion) how soft the rubber is, what matters is the shape of that rubber. 'Bite' isn't about displacing any asphalt - anyone hallucinatory enough to even imagine that was being suggested needs to step away from the hash pipe. In this context, 'bite' is about one object's edges interfacing with the edges on another surface. Turns out, in the 3D world, things aren't perfectly smooth or flat, and have corners and edges which can interfere with one another's passing.


Apparantly, you are the first to ever claim that traction has nothing to do with rubber softness, and everything to do with shape. Care to step further into the void?



danl1 said:


> For those challenged by reading for comprehension, I will repeat what I said - that all else equal, a slick will provide optimum traction on a bicycle tyre, and is the best choice. *HOWEVER,* given that a tread is being used, the direction in which it is mounted can indeed matter.
> 
> I offer the following gedankenexperimente. Into your tire, we will cut a series of grooves, spaced equally. You may include or ignore effects of differential casing flexibility at your choice. Assuming the rubber thick enough to take the abuse, it is your position that you have no preference if we cut them either longitudinally or laterally. After all, either direction will decrease the surface area equally, and will make no difference to either handling or rolling resistance, as compared to one another.


Lateral or longitudinal "cuts" have nothing to do with tread directionality - if you cut the tread longitudinally, the tire would behave the same way when rolling clockwise or counterclockwise, and likewise if you cut the tread laterally, the tire would behave the same was when rolling clockwise or counterclockwise.

Of course, lateral or longitudinal cuts could affect longitudinal and lateral traction differently. But it has nothing to do with the edges "biting" into the pavement, and everything to do with the affect on the longitudinal/lateral stiffness of the rubber, and its tendency to squirm as the tire rolls on the pavement. But regardless of which direction the tread was cut, it would have less traction than an uncut tread, because the cut tread would squirm more against the pavement.

You really should quit before you dig your hole further.


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## Slartibartfast (Jul 22, 2007)

*I hesitate to jump into the melee, but...*

...I have a question related to this very discussion.

For *off-road *use, where the tire *does *deform the terrain surface, *then* do directional treads make a difference? (I hope we can all agree that treads in general do make a difference on deformable surfaces.)

To take it further, is there a best tread for the following surfaces: 50% hard pack, 25% loose dirt and rock (1-2 in.), 25% pavement -- in the following conditions: 50% dry, 50% rain? I ask because I'm seeking such a tread. What's the best available tire with this tread, hopefully a tubeless?


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## critchie (Apr 27, 2004)

fougasg said:


> ...I have a question related to this very discussion.
> 
> For *off-road *use, where the tire *does *deform the terrain surface, *then* do directional treads make a difference? (I hope we can all agree that treads in general do make a difference on deformable surfaces.)
> 
> To take it further, is there a best tread for the following surfaces: 50% hard pack, 25% loose dirt and rock (1-2 in.), 25% pavement -- in the following conditions: 50% dry, 50% rain? I ask because I'm seeking such a tread. What's the best available tire with this tread, hopefully a tubeless?


Dude, this is the wrong crew to ask because most of what is being said is total crap. Ask any of these guys if they are tire designers, if not they should go packing.


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## Mark McM (Jun 18, 2005)

*Directional off-road tires*



fougasg said:


> ...I have a question related to this very discussion.
> 
> For *off-road *use, where the tire *does *deform the terrain surface, *then* do directional treads make a difference? (I hope we can all agree that treads in general do make a difference on deformable surfaces.)


Well, if tread direction made a difference for off-road tires, then you'd expect that manufacturers of tires for moto-cross motorcycles, ATVs, and other off-road vehicles (which have more mass and power than a bicycle) would make tires with directional treads ...

... but they don't.


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## asgelle (Apr 21, 2003)

critchie said:


> Dude, this is the wrong crew to ask because most of what is being said is total crap. Ask any of these guys if they are tire designers, if not they should go packing.


Goody, I get to stay.


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## critchie (Apr 27, 2004)

asgelle said:


> Goody, I get to stay.


Well you haven't said anything stupid yet.


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## ethebull (May 30, 2007)

Many have indicated their common sense feeling is - tread on a bike tire should improve wet traction. Tread helps on an automobile tire, right? Bike tires and auto tires are rubber on asphalt, right? 

Let’s look at the two vehicles and perhaps reevaluate this “common sense”. I’m going to use round numbers and simplify the math here.

A car weighing 2000 pounds rides on four tires. Each tire supports 500 lbs. Each tire is inflated at 33 psi. Each tire will have 500/33 = 15 square inches of contact with the road. If the car tire is 10 inches wide and totally smooth, the contact patch will be 1.5 inches front to back. The downward force, of the car tire’s rubber on the road surface, is the same as the tire pressure – 33 psi

A bicycle and rider, weighing a total of 200 lbs, rides on two tires inflated to 100 psi, each bearing 100 lbs of load. This one’s easy, the contact patch – rubber to road, will be 1 square inch. The shape of the contact patch will be roughly a 2.5” long by .5” wide ellipse oriented front to back. The downward force of the bike tire’s rubber on the road surface is 100 psi.

So what is going to cut through the standing water on the road more easily, a 10” wide bar with 33 psi of downward pressure, or a .5’ wide ellipse with 100 psi?

Car tires require grooves to channel water, bike tires do not.

The above dynamics also render the tiny ribs, herring bone patterns, etc., found on road tires, irrelevant for dry conditions. A smooth tire rolls the fastest and grips the best wet and dry.


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## wim (Feb 28, 2005)

critchie said:


> Dude, this is the wrong crew to ask because most of what is being said is total crap. Ask any of these guys if they are tire designers, if not they should go packing.


What tire designers? Marketing writes engineer-speak ad copy, then tells manufacturing what patterns and colors to crank out this year.


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## Slartibartfast (Jul 22, 2007)

fougasg said:


> To take it further, is there a best tread for the following surfaces: 50% hard pack, 25% loose dirt and rock (1-2 in.), 25% pavement -- in the following conditions: 50% dry, 50% rain? I ask because I'm seeking such a tread. What's the best available tire with this tread, hopefully a tubeless?


I feel silly quoting my own post, but I really wanted an answer to my question. Can't anyone give useful advice in this thread? I don't care about F1, moto, etc. I want opinions about mountain bike tires, ridden in commonly encountered conditions. Geez, what a beating! :mad2:


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## wim (Feb 28, 2005)

*Wrong site.*



> _I want opinions about mountain bike tires_


Try MTBR.


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## tarwheel2 (Jul 7, 2005)

Man, I was gone for a few days, and this thread is still going.

To all those who are skeptical of my observations that the Panaracer Paselas have more rolling resistance when mounted "backwards" I would say:

Why would Panaracer put directional arrows on the tires if it didn't matter?

All theories aside, observation and experience are the best teacher. I am apparently the only one here who has tried this "experiment." I rode my bike for several days with the tires backwards, and then switched the tires the right way. And my observations were that my bike rolled noticeably faster with the tires oriented the correct direction. It felt faster, my maximum speeds were higher on downhills, and my average speeds were higher. I am convinced that the Paselas have less rolling resistance when mounted with the directional arrows pointed the right way. If you don't believe me, then buy some Paselas and try the experiment yourself.


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## Slartibartfast (Jul 22, 2007)

wim said:


> Try MTBR.


Yeah. Will do. Tried earlier today, but had trouble with the site.


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## Slartibartfast (Jul 22, 2007)

tarwheel2 said:


> I am convinced that the Paselas have less rolling resistance when mounted with the directional arrows pointed the right way. If you don't believe me, then buy some Paselas and try the experiment yourself.


I believe you. Some are clouding the issue of directional rolling resistance of treaded tires by talking about the difference between treads and slicks rather than the difference between properly and improperly mounted treads.

Here's an easy way to understand directional rolling resistance: Imagine a tire that's slick except for one wedge-shaped lump an inch high and two inches long. When rolling one direction the pointy end of the lump hits the pavement first and the tire rolls easily over the lump. When you dismount the tire and turn it around, now the blunt tall end of the lump hits the pavement first and minutely slows the bike as the tire rolls over it.

Now imagine dozens or hundreds of wedge-shaped lumps 1/4 inch tall and 1/2 inch long. That's basically what directional tread is. It may not be *better *than other tread designs, but it *will *mess with rolling resistance if mounted wrong.

I admit to writing this authoritatively as if I were a tire designer, when actually I just used common sense.


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## asgelle (Apr 21, 2003)

tarwheel2 said:


> Why would Panaracer put directional arrows on the tires if it didn't matter?


Marketing, anyone?



tarwheel2 said:


> All theories aside, observation and experience are the best teacher. I am apparently the only one here who has tried this "experiment." I rode my bike for several days with the tires backwards, and then switched the tires the right way. And my observations were that my bike rolled noticeably faster with the tires oriented the correct direction. It felt faster, my maximum speeds were higher on downhills, and my average speeds were higher. I am convinced that the Paselas have less rolling resistance when mounted with the directional arrows pointed the right way. If you don't believe me, then buy some Paselas and try the experiment yourself.


If you want to do an experiment, there are instructions at biketechreview and the wattage forum on how to perform the test and reduce the data. All you are doing is couching your opinions as facts. Feelings are not data.


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## ethebull (May 30, 2007)

fougasg said:


> Now imagine dozens or hundreds of wedge-shaped lumps 1/4 inch tall and 1/2 inch long.


I ride a pair of 32mm Pasela's. The rolling surface is Very fine file tread (about100 tinny weensy .5mm tall pyramids per square cm) broken up by 2mm deep square shouldered grooves cut diagonally every 12 mm or so. This is Not A Dirt tire! 

Since Tar is convinced the tires rolled better after re-installing them in the "proper direction" I would conclude that while removing the wheels and reinstalling them, he corrected an unrelated hidden cause - like the brake was dragging or the tire was rubbing on the chain-stay. It was not the tire direction.


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## Slartibartfast (Jul 22, 2007)

Hmmm. Makes you wonder why it even has tread.

I think the principle I described holds true down to some point; agree it sounds like your tires are beyond that point.


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## Forrest Root (Dec 22, 2006)

asgelle said:


> If you want to do an experiment, there are instructions at biketechreview and the wattage forum on how to perform the test and reduce the data. All you are doing is couching your opinions as facts. Feelings are not data.


Careful, you're gonna shatter the worlds of many people on bike forums all over. Didn't you know that feelings trump science? Gee, I feel like when asleep and dreaming, I'm in another world. Since I feel it, it's obviously true, then, that I am in fact in another world, with a different spatial location than the one in which I am sleeping. Q.E.D.


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## Slartibartfast (Jul 22, 2007)

Forrest Root said:


> Careful, you're gonna shatter the worlds of many people on bike forums all over. Didn't you know that feelings trump science? Gee, I feel like when asleep and dreaming, I'm in another world. Since I feel it, it's obviously true, then, that I am in fact in another world, with a different spatial location than the one in which I am sleeping. Q.E.D.


My Colnago feels better than my Trek -- can't prove it, but it's true. Not true in the absolute sense, but true enough that I ride the Colnago unless it's really bad weather.

My Colnago rolls faster with Zipp wheels than with DuraAce. Can I prove it? Not with the precision I could in a lab, but since it happens over and over again on the same downhills I believe it to be true.

How do you know you're not in another world while dreaming? Show me the data that proves you're in the same world while dreaming.


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