Originally Posted by
urbanknight
I could be wrong, but most people use tubulars to be fast, not to last long. Even when I weighed 120 I pumped my tubulars up to 140 psi for lower rolling resistance. I got as many miles as I needed before the rubber started to age and lose grip, and the ride was smoother at 140 psi than any clincher I ever rode at 110.
Problem is that this is really a fallacy, more pressure does not mean lower rolling resistance, there are more factors involved. I would say pump them up to the max 12 bars if all you do is ride on perfectly smooth metal drums (rollers) but the road has holes, dips, chips, and generally rough surfaces and pumping up your tires too hard will cause it to bounce on the rough surface instead of conform to it.
Ride it however you want, but just know that more pressure does not equal lower rolling resistance. Look at this post by Leonard Zinn, look carefully at the last two paragraphs:
Dear Tom,
I agree with Josh, and yes, there are lots of test numbers to back it up. It is the same reason a suspension bike (or car) is faster over rough ground - less mass must be accelerated when bumps are encountered, thus saving energy and reducing momentum loss. Every little bump that gets absorbed into your tire (another reason that supple, handmade casings roll faster than stiffer, low-thread-count casings) is a bump that does not lift the entire weight of you and the bike.
You feel fast on a rock-hard tire for a similar reason that people like the feel of stiff brakes (V-brakes with the levers set on low leverage). The brake feels good and stiff because you are doing more of the work. If you increase the leverage, the brake feels spongy, because the extra mechanical advantage allows a modest pull to squish the pads.
When you ride a tire at 170psi, the bike feels really lively and fast. That is because you are being bounced all over the place by the surface roughness of the road. However, every time you are bounced, energy you applied to the pedals to get you up to speed is lost. Also, you have less control of the bike, so it feels like it is going faster, even though it isn't. Ever notice how driving down the highway at 75mph in an old Jeep feels crazy fast, and you can cruise smoothly along at 100mph in a nice Saab or BMW and feel like you are going maybe 60mph unless you are looking at stationary objects passing by?
There is simply no question about it; rolling resistance tests conducted with bicycle tires rolling over surfaces akin to normal road surfaces always indicate the lowest rolling resistance at pressures a lot closer to 100psi than to 170psi! Years ago, for example, I saw results like this at the Continental tire factory. I was told of similar results at a number of other tire factories I have visited.
Lennard