Tire pressure should be matched to the roughness of the surface. The rougher the surface, the more you want to back off from high pressures. Around where I live, roads don't have a lot of potholes, but there are a lot of older "chip-seal" roads that'll just rattle your bones. I run 23s at 90 pounds or 25s at 80 pounds. The bike is faster and more comfortable that way. A rough surface and a high pressure tire result in a million little impacts that push your bike backwards.

Only downside to the lower pressures is the risk of pinch flats when whacking into a pothole. I had one last summer hitting a pothole at 35 mph. I had 23s on the bike at 85 pounds that day.

On super-smooth surfaces (like a velodrome), higher pressures can help you go a little faster.

Marcel-

The higher the PSI, the lower the rolling resistance. A lower rolling resistance means more speed, less comfort, and less likely to flat.

Litherland

[reply]
The higher the PSI, the lower the rolling resistance. [/reply]

On smooth surfaces such as a velodrome, yes, but on the roads that we typically ride on, not true. See Dan's (unfinished) report on rolling resistance at
[url]http://www.slowtwitch.com/mainheadings/techctr/rolling.html[/url]

A

The tire needs to deform over the imperfections of the road surface. Too high of pressure and your wheel will be like a ping pong ball, bouncing all over the surface spending time going up and down, not forward. Your daily air pressure should also take into account how long you'll be riding (comfort) and what the route will entail (corners)

I'm typically 85 psi with my 25c Michelin Top Comforts.

SuperDave

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https://www.kickstarter.com/...bike-for-the-new-era

high pressure also equals more blowouts and after a certain point it seems like more flats period. I weigh 150 and run 110 on my road bike, 120 on my Softride. A friend of mine just tried 150psi for the first time and had a blowout while leading a tri downhill doing 30+, blew the tire right off the rim.

For training, I use larger 25mm tires pumped about 100 psi. For racing, higher pressures are better but do not go to the maximum pressure recommended on tire only, different rims hold tires differently. I have had problems using 19mm tires on Corima clincher rims. Tires blow out at 120~130 psi, sometimes in races. Recommended pressure on Corima rims at 110 only. I went to 23mm tires at 115 psi and no more problems. May be a little less aero but much safer and Dan uses 23's so they are well tested. I even switched to 22mm on tubular wheels since they ride better than 19's. Size matters.

NJ Biker and others-

With all due respect, I don't see it. First of all, I do not mean to suggest that you should run your clincher tires at 150 psi. As in most cases, reason should be applied. You should never inflate a tire past the manufacturer's max pressure and max pressure doesn't mean suggested pressure. Second, Dan discusses tred patterns and tire width, but I see nothing about PSI except for a mention of "sufficient pressure." Am I just missing it? Finally, my post intended to show that there is a balancing act between performance\durability\comfort. The answer is never as simple as saying, "the best tire pressure is..."

Litherland