Originally Posted by
skookum
It is a good thing that people are testing tires for rolling resistance. I'm not sure that these guys are doing it the right way. There are problems with testing tires on drums. The drum pushes into the tire in a way that doesn't happen on a flat road. A stiff tire will not deform as much and will record a lower rolling resistance than a supple tire.
We push the tire into the road instead; the net effect isn't that much different, and drum testing makes it much easier to test, and is reasonably representative of tire rolling resistance differences on quality road surfaces. You could do definitive testing with a bunch of different tires, a stretch of road without traffic or pedastrians, a power meter, and a lot of repetitions. Would be a huge endavour, and you'd expect the results to correlate closely to drum testing, nevertheless. I mean, look at the top spots for road bike tires, all dominated by high end expensive tires people actually race on... as you'd expect.
When the road surface is bad (there's a section of road closed off to most traffic where I often train with a really crappy road surface) then, well, while I don't have a power meter on the bike it appears that lower pressures to give more cushioning are actually faster for the same effort (again, I can't decidedly confirm without a meter). Which is kind of unsurprising, people who race on mountain bikes do so with, from our point of view, very low pressures. They for sure don't do it because it's
slower.
I use 42x559 Marathon Supremes on my touring bike, and going for low rolling resistance was one of my motivations for picking the tire, and it does seem to roll quickly, especially where the road surface is good and I pump it up to a pretty high 75psi - not as good as a quality road bike tire, though.