A muddy race in Portland finally made me understand tire pressure

I was working the pit at the Cascade Cross race last fall, and this guy came in with a bike caked in mud... he couldn't get any grip on the off-camber sections. We dropped his pressure from 40 psi to about 25, right there in the rain. The difference was instant, he stopped washing out completely. I used to just go by the sidewall number, but now I always ask about conditions first. What's your go-to method for dialing in CX pressure on the fly?

5 comments

5 Comments

schmidt.iris14d ago

Keep that air high and ride with real technique, low pressure just masks bad handling. @the_julia didn't learn anything the hard way, she learned the easy way by giving up on skill.

jesse_lopez141mo ago

Ever try to explain tire pressure to someone who only rides on the road? My buddy saw my cross bike after a race and asked why the tires felt so soft. I told him it was for grip in the mud, and he looked at me like I had three heads. He just kept pointing at the sidewall number. Some things you only learn by sliding out a few times. Now I just go by feel and the sound the tires make on the ground.

max_patel11mo ago

Yeah, that sidewall number is more of a scary legal thing than a real target. I ran my gravel tires way too high for months because of it, until I washed out on a loose corner. Now I just squeeze the tire before a ride, and if it gives a little, I know I'm good. My roadie friends still think I'm crazy for letting out air on purpose.

the_julia1mo ago

Learned that lesson the hard way too!

skyler_kelly6914d ago

Nah, I gotta push back on that whole "low pressure masks bad handling" take. I've been running cross races for years now and there's a reason the pros are dropping pressure into the teens when it gets really nasty. Sure, technique matters a ton, but physics is physics. You can have the best bike handling in the world and still slide out on wet roots at 40 psi because your tire just can't deform around the surface. It's not about giving up on skill, it's about understanding that your equipment needs to match the conditions. I adjust my pressure based on the course and the weather, and I'm not gonna pretend that's lazy riding.