Tire pressure - is this really right??? (Page 2)

You misunderstand me.  My brake adjustment is correct. 

If I were to put 25s on a std rim the ture will bulge out enough that it will probably not go past the brake pads when the calipler is open.  With wide rim tires, which I am suggesting I may try (and you apparently use) not only would the brakes pads be wider but the 25mm tire would not bulge out beyond the rim as much and the release lever would open the pads far enough to allow an inflated 35 to pass, as you are experiencing.

Very interesting discussion. I always train at 120psi on clinchers and race more like 140psi for racing on tubulars. We don't have a lot of chip seal out here in the Soutwest, roads tend to be pretty smooth. Still, I wonder if I should lower it a bit... Might post this over on ST as well and here what they have to say..

Few things on the C2s. One, you will have to reset (widen) your brake calipers from what you have now. Two, a 25 has and will work on a C2. Three, you may not want to use a 25 on a C2, as the C2 is optimized for a 23 tire (yes, you can use, but then you may want to consider another wheel).

Bryan,

Even on the smoothest roads here, I get the best results with my tubulars at around 115psi (I normally race at 170lbs).  I would definitely consider dropping the pressure down for race day.

Shane

I'll give that a try, Shane.

Well, I did post this on ST and here's one of the better responses so far:

"I decided to ask some of the guys who work at triathlete mag, and this is what they said back.

If you were racing on a perfectly smooth surface, you would want a rock solid tire. Train tracks are the most efficient rolling mechanism out there because it is two incredibly hard, perfectly smooth surfaces pressing against each other. On the opposite end of the spectrum is a full suspension mountain bike. Even though these bikes mush and flex underneath the rider, they are much more efficient from a rolling resistance perspective than a hardtail mountain bike. This is because a less forgiving bike gets bounced off the surface and the rider's energy is being used to climb small hills every time they hit a rock, root etc. The same bouncing effect happens when riding on the road with an over inflated tire because pavement is not perfectly smooth. If the tire is over inflated, the rider is constantly skipped off the pavement by the chip-seal which, just like the mountain bike scenario, is akin to climbing tiny hills.

The ideal scenario is to inflate your tires as much as possible without causing the rider to be skipped off the pavement. This means that inflation is based upon rider weight, tire flexibility and road quality. For a person like yourself, you could go as high as 135, maybe 140 on incredibly smooth pavement. On standard pavement you will be better off around 120psi and even lower on rough pavement. 105-110 could be appropriate. Sorry I can't provide you with a specific PSI that you should always run but the reality is that different road conditions call for different pressures.

Aaron Hersh
Senior Editor, Gear and Tech "

So the questions still seems to be up for debate.

Ummm, I just inflate them to right around the recommended maximum inflation.  Usually about 5 psi below.

Edited by pga_mike 2010-03-26 8:45 PM

Yeah.  I read through that thread.  It looks like the answer for me is 'lowering it a little is probably right'.  Interesting stuff, but not very definitive.  Maybe it's the best we'll get though.

Anyway, thanks for the replies everyone.  It was helpful.