Quote Originally Posted by liza View Post
But tire pressure is basically a trade-off. Higher PSI = harsher, but faster ride. Lower PSI = plusher, but slower ride (lower PSI will be slower b/c more of the tire contacts the road, thus there is greater resistance).
Admittedly, there is some debate out there as to whether running tires at higher pressures increases speed on anything but the smoothest of surfaces, e.g., a track. That said, IMO stopping shy of max pressure can actually increase speed on the average road surface. Running at really high pressures will make you bounce more, causing you to lose speed as your tire loses contact with the road. Running a little less than max can also provide better cornering, which will also increase speed.

I maintain that it pays to play around with tire pressure both front and rear to see what pressure feels good to you. The ideal pressure at which you both maximize both speed and safety, achieve a comfortable ride and avoid pinch flats will depend on your weight, the tire tire size, rode surface and weather. Finally, you can always run a wider tire, like a 700 X 25 cc, without compromising much in speed if you'd like a plusher ride.

For more on tire pressure, take a look at http://sheldonbrown.com/tires.html#pressure