Friday, August 6, 2010

A word on tires...


I've often been telling people for the past few years that the tire pressures I prefer are lower than what is perpetuated by the common wisdom of the masses. When I tell a person 110 psi max for their weight when they have been running 130 psi for years often results in an expression that says that I just grew a unicorn horn on top of my head. Here's the reasoning behind my tire pressure evolution.

I used to be a high pressure guy. I rode best when I weighed about 150 pounds and I would pump up my road tires 120-130 psi for all rides. It felt faster. If some was good then more must be awesome. I went happily skipping down the road and sliding through corners relying on sheer skill and courage to try and ride like the racers of the time. When I made the jump to tubulars, man, 140 psi became easy and knew guys who ran 160+. That's on road-not track tubulars.

Years later I noticed that tire side wall recommended pressures seemed to be climbing. Some even went as high as 140 psi for a clincher. It was like a tire psi cold war. On roads that were rough enough I noticed a unpleasant feeling of bouncing rather than rolling across the surface. I tried all the major and most of the smaller brands of tires. I compared Vittoria EVO CX to KS tires. Conti GP4000s to regular Grand Prix. Vredestein, Michelin, Challenge, etc.

I started riding with less pressure. It felt good. I got feedback from people running 25c rather than 23c tires. Anyone heavy enough to exert more forces than the average person on the tire came back with positive comments. I spoke with some of the smart people at Vittoria and Continental at trade shows to get their opinions. Almost universally they said all of their in-house people ran much lower pressures that what was on the sidewalls. Most of the employees run about 100 psi I was told. I started doing this myself. I liked it. I started telling others.

Companies started to validate what myself and many other cyclists were discovering. Mavic states that if their wheels are run at >130 psi they won't warranty the product. Now, rim companies are taking cues from mountain bike influence and widening the rim bed to accommodate a wider tire contact patch which improves ride quality. The age of running 18, 19 and 21c tires are gone. It's not even more aero according to some companies testing. The tire feels like the casing is working to soften the ride and absorb road imperfections. The tire feels like it's putting down a much more solid footprint when leaning into a corner. Flats are diminished. I'd be hard pressed to have anyone convince me that a 25c tire is much slower than a 23c tire in real-world conditions.

Just for reference here is a chart that Michelin has been publishing for a few years regarding tire pressure. Take a look and do some experimenting and see if this works well for you. If your experience has led you to a different outcome than mine, do what works best for you. Just making a small point here that what works for Jack will not always work for Jill and tire pressure is an easy way to potentially improve performance on your next ride.