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Wider is faster!


The truth about rolling resistance:

Wide tires offer more control, more comfort and more fun. While this has become more widely accepted over the past few years Sport Scientist Peter Nilges, was not too interested, he was more concerned with speed.

The avid, German League road racer wanted to determine the best tire width and air pressure combination for fastest performance. He completed 300 test-rides with SRM cranks to establish the exact energy consumption for his thesis “Road Rolling Resistance”. He tried three different tire types in three widths at 20 psi, 30 psi, 45 psi and 55 psi on road, dirt track and cross-country

The results were clear. Higher pressure was only faster on the road. Off-road rolling resistance was lower, the wider the tire and the lower the pressure. This was similarly true for dirt tracks, soft forest roads or cross-country and up to 40 Watts could be saved in extreme off-road conditions; poor acceleration caused by higher tire weight being generally compensated for. Explanation: A tire at low inflation pressure adapts better to uneven surfaces. It sinks into the ground less. Overall it suffers less retardation. Narrow tires are only recommendable for lightweight riders, weight saving or extremely muddy trails.

Rolling Resistance

                  Tire Pressure

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Would have liked to see test with machine instead of rider

Submitted by Timm (not verified) on Mon, 11/26/2007 - 10:07.
I would have liked to see such a test performed with a machine instead of a human who is subject to fatigue and psychological effects (such as confidence in one tire over the other), on his performance, as well as variations on his line of attach on the trail followed. If you used a 4-wheeled cart fixed-speed, weighed down to simulate rider weight, driven by an electric motor, and timed it’s performance to cover a given course, then you have reliable data. (the cart would have a constant load of electricity sent ot the motor, thus the slowdown would be measurable, and the motor doesn’t get tired or have more confidence in one tire over the other). The test that was done here sounds too much like “lets get a well-known pro-rider for credibility so no one dares question the results, have him test tires, so we can prove a point on our website and increase sales”… (what do you think, that people are stupid???).
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Shannagin

Submitted by Destind (not verified) on Fri, 08/03/2007 - 10:08.
This data may be true for certain tires in specific conditions, but assuming that a rider is using a low rolling resistance tire-a semi slick- the higher pressure does not push the tire lugs further into the ground as the article states, but instead will remain firmer creating less rolling resistance, making it faster. The scientific data yeilded by these experiments must be seriously questioned as there was no control used, nor were both tires made from the same compound and by using comparisons like these with different compounds nearly any conclusion a researcher wanted could be reached by using different rubber compounds. Thats all for now, Destind PS Dont believe everything you read.
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Cobblers

Submitted by WA (not verified) on Wed, 06/06/2007 - 14:07.
“poor acceleration caused by higher tire weight being generally compensated for” Generally? That doesn’t sound very scientific. Let’s all run 5.0 tyres at 5psi in our next XC race then. It appears that this study assumes a perfectly flat surface and a rider who experiences zero fatigue. Add hills and distance and I’d hypothesise that weight advantages will rapidly start to plop all over all other considerations. i.e. it’s not worth the Marin it was ridden on.
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Questioning your questioning

Submitted by RMR (not verified) on Sat, 09/22/2007 - 20:28.
WA, You raise a valid point about the lack of detail given, but I disagree with some of your statements. First, distance shouldn’t matter. I can’t see how a wide, soft tire could have less rolling resistance over a short distance, while a narrow, hard tire would have less over a long distance. What’s true for a short distance should be true for a long distance. I’m not clear on how you’ve determined the assumption of a flat surface. If you mean it in the large scale, such as hills, then I agree this warrants a more detailed explanation. If you mean it in the small scale, such as trail roughness, then it sounds like that’s the where the wide, soft tires have the greatest advantage. Also, I’m not clear on why you feel this test assumes a rider who experiences zero fatigue. If the rolling resistance is less with the wide tires, then a ride on such tires should experience less fatigue. Obviously, aerodynamic drag and increased mass will become serious factors at some point - and probably well before reaching “5.0 tyres”. It’s not clear where those factors begin to dominate, but it would seem not within the scope of this study. WA, you dismiss the validity of this study, then “hypothesise” (sic) that weight is a more significant factor. At least this study attempts to use some science to back up a statement; I see none of that to support the weight theory.
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off-road tire press vs rolling resistance

Submitted by Terry Ryan (not verified) on Thu, 04/19/2007 - 09:50.
Very, very interesting. I always thought higher pressure reduced rolling resistance off road and on road. I “thought” this, but could not prove it one way or the other. I would sure like to read the test procedures and individual test data. Thanks, Terry Ryan, mountain biker
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Check this description in

Submitted by Anonymous on Wed, 01/09/2008 - 08:12.

Check this description in the UK page.
Rolling resistance is on page 14 - 15

http://www.schwalbe.co.uk/shopdata/files/tech-info.pdf

Regards
Yngve

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interesting

Submitted by Anonymous on Tue, 04/22/2008 - 17:36.

I think those who doubt about scientific approach missed the key word “SRM cranks”. I guess it means rider or machine doesn’t matter.
On the other hand, I wonder how could best riders miss such opportunity before this study? Or “Road Rolling Resistance” is considered as an isolated measure and it doesn’t imply better sport results?
Also there is a weak guess that better results could be a consequence of the increased outer wheel diameter caused by wider tire… the study should be performed along with the 29ers to check this guess.

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