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???).

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.

"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.

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

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

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.

I sure ride alot. I get 3-4 days a week up my local trail. That's right...trail, not plural. Where I live there is one trail and I ride the same essential loop a few times every week. Over the last few years I have experimented with several tires at several PSI levels and I find my own reality to be different from what I have read above. When I lower my PSI or switch to a larger volume tire I can definitely feel it. Does not matter to me what the rider found in his study, my personal experience has been very different. Am I the only one?
Palm Springs Desert Rat

I am pleased to see the critical reaction to this article by people who are clearly very experienced in XC riding. The conclusions don't seem to align with my own personal experience or preferences.

Dissenters first read not just assume what you believe is correct because you are in fact 100% wrong. The above is called an abstract, a full release of the actual test data would be great though most likely would indecipherable to the uneducated and unaccustomed reading scientific literature so generally this is done so the uneducated can get something out it. Yes a machine was used to measure the rider energy/power to travel through a section to be measured. Do you know what an SRM is look it up. A real rider must be used as there is no machine that can actually ride a bicycle on dirt rocks ect. I have done less scientific study of my own though did control as many factors as could and yes a wider tire at lower pressure on dirt rocks roots is always faster. Just because your getting bounced around more because of the skinny's are pumped up you feel your going faster but you are not rolling faster down the trail period.

http://www.bernhansen.com/Teste/Dekktrykk,%20bredde%20og%20knastens%20in...