On Dec 3, 2009, at 9:09 AM, newenglandbike wrote: > Not to throw a wrench in your plans for the AHH, but Jan Heine et. al. > recently published results of an extensive test involving various > tires/widths and speed, and they found that rolling resistance is a > *weak* function of tire width. In other words, tire width had > little to do with rolling resistance. They found that wider tires at > moderate pressures are actually faster than narrow tires at high > pressures. I do not have the issue of BQ (I'm working on getting a > copy) but is in Vol. 5, No. 1 (Autumn 2006). > > Does anyone here have the article?
Yeah I do as do several of us, and Jan reads this mailing list too. I've always had some problem with that particular report which I've discussed with Jan at great length (without convincing him nor he convincing me). However, the results did match pretty well with what one would expect (tries with thick rubber being slower, tires with knobbier treads being slower, etc.). However in the last issue of BQ they published a *very* interesting test using a Tune PowerTap to measure the power necessary to maintain speed over smooth and rough pavement. In both cases they found the fatter, softer tires (a Panaracer Pasela 700 x 37) to take less power than a skinny hard tire (Bontrager 700 x 25) to maintain the same speed. Over smooth pavement the differences were smaller but still significant; over rough pavement the differences were startling. I found this article fascinating and hope that Jan does more with it. Directly measuring the watts it takes to roll a tire seems to me to provide the most immediately useful data about tires. Exciting stuff. (OK, I'm a geek). The short version is that skinner is not necessarily faster; higher inflation is not necessarily faster. On the steel drum rolling resistance machine, all other things being equal, wider is faster and harder is faster. On the road, wider is faster and softer is faster. There is no doubt a point of diminishing returns or we'd all be riding Pugsleys with 4" wide tires. The main issue with rolling resistance is hysteresis, the loss of energy in flexing the tire and tube. Thinner tread, supple casings, etc. roll faster. This appears to be true on steel drum RR rigs and on the road. In practical terms, I did many crits, road races and club rides on my cyclo-cross bike with Avocet 700 x 32 slicks. I was just as fast on that bike as on my "race" bike with 700 x 23s. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To post to this group, send email to rbw-owners-bu...@googlegroups.com. To unsubscribe from this group, send email to rbw-owners-bunch+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
