Originally Posted by
javal
I wont argue about the recommended pressure, but max pressure (or even a bit harder) is the easiest way to make a bike go faster on even surface. Less rolling resistance + less friction = speed.
Maybe. The best rolling resistance does not necessarily occur at super high pressure. Deflection in the tire sidewall as you ride is not necessarily bad, either.
Don't get me wrong. I'm mostly in agreement with you, but I would not have 100% confidence in saying that the fastest thing for any given tire is always max pressure.
I
do, however, have 100% confidence in saying that the harshest ride you can get from a given tire is at max pressure!
I would leave the racing to racers and instead inflate your tires appropriately for their size, your total bike weight (mainly your body, but trailer or panniers would count), and your riding conditions. Smooth road-- yep, go high. Bumpy road, lower pressure but enough to where you don't get pinch flats. Offroad, same as bumpy road although if it's bump-free you can go lower pressure still to get significantly better traction.
Real world examples of my bikes:
Road bike has 700x25 Conti GP 4 Season. I weigh 175 pounds. I can run as low as 95psi in the rear for more comfort (and not get flats), but I can feel the tire squirm and I am much happier at 110psi. Despite a max rating of 130psi, I run no more than 120psi because I don't want to wear the center of the tire excessively.. the full tread is in fact intended to be used.
Hybrid bike has 700x35 Kenda Kross Supreme. I run max pressure on the sidewall, 85psi rear, on the road because this tire is made for mud and sand and it is terrible on pavement and this helps significantly. Gravel roads and basic cross-country riding, I run 70psi to balance rolling and grip. Technical singletrack I run 55psi unless there are a lot of big rocks or >1 foot drops / jumps. Then I run up to 70psi.
I don't currently ride a proper MTB but when I did you can go below 30psi offroad thanks to the huge volume of air in the tires.
All the above is rear tire only. For the front, decrease pressure by 5-10 psi depending on your riding position and thus weight distribution. Most hybrids will want 10psi stagger since the rider typically is fairly upright.