DeeDub

I weigh 160lbs my bike weighs 20lbs How much pressure should I be running in both 32c(faster courses) & 35c(muddier courses) tires?

Ronsonic 

Enough that you don't pinch flat. Depends on how you ride and what sort of obstacles and edges on that course. Start high and then get braver as your experience tells you what you can get away with. A smooth, deft rider of the same weight can get away with a lot less air than a guy clanking his way around the course.

Ron

dc70

Anyone have a guidline for tire pressures on a mtn bike with 26 x 2" kenda tires?
Wet grass, dirt/mud trail type course.

Is it better to go towards higher pressures? less resistance, etc.

Iffacus

When warming up on the course I always start off with my tyres at about 40psi, and as I find out what the course is like drop the pressure a little at time. Usually I don't go below 25psi normally somewhere between 30-35psi.

But it really does depend upon the course and your smoothness as a rider. Just go out there try some different pressures and find what works best for you,

Timo

It depends. Do you run tubulars or clinchers?

JimmyMack

It's hard to say without knowing the conditions. Let's say the course is double track moist dirt, then here are some basic numbers.

Clinchers start at 50 and 50. Warmup laps might feel like you are riding in an ice rink, so let some air out to allow the front wheel to "taste" the dirt. I usually end up somewhere around 35 up front and 45 in the rear. This is known with a final pump check.

Tubulars start out the same way, but the pressure dropps significantly. The tires have been run as low as 25 up front and 35 in the rear.

You have to get used to the flat tire feeling. if you're not used to it just start at 50 and try that for a while. Maybe keep the rear at 50, and get used to running a flatter front for increased steering. Eventually you will need a bit less pressure in the rear to work well with the low pressure front.

92degrees

I haven't been running less in the front. Is that the generally accepted strategy?

JimmyMack

It works for me. Sometimes the rear feel like it has enough traction but the bike doesn't seem to steer to well. Maybe you have experienced this feeling.

The rear is sticking in the turn. You are leaning and turning. The bike still seems to be going straight, and you thinking “No, no, no stupid bike. You’re doing it all wrong. Go around the turn, not straight into the course tape. Dumb bike! Sheesh!”

When that happens, it’s time to stop and take just a bit more air out of the tire. Next time around that turn usually hooks up then. If not, maybe a bit more air. Before the race you might want to pump a pound or two back since you will be riding harder at race pace.

Eventually an agreeable tire pressure will come out of the trial and error testing. Three short pssst, pssst, psssts are all you need to relieve some pressure and gain some traction.

92degrees

Cool. I'll try that. I run less pressure in the front on the road, but that's more about dampening vibration (I think) than steering.