CX: Only 40 psi? Really?

/6 Comments/in /by

In last week’s cyclocross lesson with Brandon Dwight, national CX champ and owner of Boulder Cycle Sport, the first question I asked was,

“What tire pressure should I run?”

I’ve been riding my S-Works Tricross for about a year now, and I’m enjoying it more and more. With 32C cyclocross knobbies at 80psi, the bike feels effortless on smooth trails, but on rough surfaces I feel like I have to go fast, stay high in the bumps and rock serious chatter-pump to keep from getting beaten up.

My logic for 80 psi has been:

I usually run about 40 psi on my 2.3 Eskars. A 32C ‘cross tire has about half the cross-section, so doubling the pressure makes sense. Right?

Wrong!

When I asked Brandon about tire pressure, he suggested more like 40 psi — maybe down in the low 30s for some courses. Even lower with tubulars.

What? Crazy!

Yeah, apparently that’s what ‘cross people do. I followed Brandon’s advice and — wow — my already sweet bike feels even sweeter.

I’m still gonna try to go fast and stay high in the bumps.

Drop bar braaap!

— Lee

PS: I’m leaving for some NICA coach training in Norcal. When I return, I’ll show you Brandon’s tips for smooth dismounts, carries and remounts. Clang clang clang go the cowbells!

Know more. Have more fun!

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6 replies
  2. E says:

    Word to rolling low. East Coast check-in. Panaracer Rampage 2.35 rolling 26F/28R any lower and it tends to fold on the harder turns. Oh yeah rolling on tubes and pinching isn’t a problem. Low pressure = Faster roll + greater control

  3. Stefan says:

    Hi Lee,

    Love the site, my day is not complete till I check out what’s new on leelikesbikes.com.

    I am confused. I thought that a higher pressure would roll faster, less squerm = less friction therfor a faster roll.
    And a lower pressure would provide more traction. Unlike you Lee, I’m not that good at explaning my thoughts without my hands. And your facial expressions to let me know if you get the jist of what I am trying to convay.
    Excuse the spelling.
    Thanks
    Stef

  4. leelikesbikes says:

    Huh? Whu? … 🙂

    High pressure is faster on smooth surfaces.

    If the surface has any bumps at all — even tiny ones — lower pressure tends to be faster. A softer tire absorbs irregularities and transmits less force to the bike/rider. This is especially noticeable on a fully rigid CX bike vs an all mountain MTB. In corners, softer tires (but not so soft they wallow) deliver more traction and higher speeds.

    I just rode a short/tech loop five times on the Tricross at 40 psi, and it was awesome. WAY better than at 80 psi. I’m starting to feel like I can rip on this bike.

  6. leelikesbikes says:

    I’m working on it!

    Racing the Tricross on Oct. 31. Gonna ride it as much as I can and sleep with it.

    I think I need to seek a pinch flat and rail a turn until I lose both wheels, just so I know the limits.

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