[nd89sc88]

I'll admit to being a total dunce when it comes to this topic and so I figured I'd better ask . . .

Does lower tire pressure increase speed for xc racers? I only race once a year (Chequamegon), and it's not technical in any way - just lots of climbing, fire roads, etc. I have always thought I would better off with higher tire pressure and slicker wheels (to a point) for less rolling resistance . . . but low tire pressure seems to be all the rage, and I don't understand why. Can someone enlighten me?

Thanks in advance,
Bill

 

[bholwell]

Does lower tire pressure increase speed for xc racers?

Yes, until you get a pinchflat or roll a tire, and then, not so much.

Seriously, though, the ideal inflation pressure is always changing with the terrain. For asphalt stretches and super-smooth hardpack, higher pressures are faster. On bumpy rooty and/or rocky terrain, lower pressures help absorb the bumps, and as a result your forward momentum is not converted into up and down motion.

The key is experimentation. Try varying your pressure in small increments, and pay attention to the subtle differences. There's a good sticky in the wheels & tires forum -> http://forums.mtbr.com/showthread.php?t=561602

 

[shiggy]

Yes, until you get a pinchflat or roll a tire, and then, not so much.

Seriously, though, the ideal inflation pressure is always changing with the terrain. For asphalt stretches and super-smooth hardpack, higher pressures are faster. On bumpy rooty and/or rocky terrain, lower pressures help absorb the bumps, and as a result your forward momentum is not converted into up and down motion.

The key is experimentation. Try varying your pressure in small increments, and pay attention to the subtle differences. There's a good sticky in the wheels & tires forum -> http://forums.mtbr.com/showthread.php?t=561602

...and time the runs with different pressures. Feeling are very deceiving. Most riders doing comparison tests will say they were faster when the clock says otherwise. Been there...

Many times, what you are feeling is the bouncing around and reduced control. Less drama usually = faster overall.