Forum home Mountain biking forum MTB beginners

Bit of help please - adjusting front suspension and tyre pressure

thyjonesthyjones Posts: 4
edited September 2019 in MTB beginners
Hi All,

I've purchased a second hand bike to get back into riding, it has been quite a long time so am a bit rusty...

I know how to add air to the forks (Rock Shox) based on weight, but on the right hand side it says Compression right a clockwise arrow pointing to a lock symbol. What do i need to do with this if anything? Ive found a manual online but it doesnt advise.

Secondly, the tyres are tubeless with an advisory of 65psi written on the tyre, do i go to this full amount or does it depend on conditions.

Sorry for the basic questions.


  • david7mdavid7m Posts: 635
    The lock means the forks are locked to help with climbing/ when you don't need travel absorbing your effort. They will still move, but should be considerably harder.

    65psi is the maximum. What tyre and size are they? How heavy are you? 30psi probably a good starting point for off road.
  • The RookieThe Rookie Posts: 27,743
    thyjones wrote:
    I know how to add air to the forks (Rock Shox) based on weight.
    No, you should be setting sag, setting by weight usually ends up with them far to stiff.
  • Setting air pressure in forks by weight isn't exact but it gets you in the right place. Setting them using sag is how much they compress when you sit on the bike. The rough guide is that they should sag 20-25%. There are guides on-line for how to do that and plenty of discussion on this forum.

    65psi is max tyre pressure and that would make just about any MTB tyre rock hard! Unless you were tarmac bashing, I wouldn't have them anywhere near that. Tubeless are also meant to be able to run at a slightly lower pressure than tubed, so try 30-35psi and see how you get on. Different tyre sizes, terrain, riding style and personal preference all affect pressures. Some people like 22psi and others (like me) prefer nearer 35.
    "Ride, crash, replace"
  • ^what they said.

    30psi in the tyres is a good rough starting point. I run 27psi front, 33psi rear. (I weigh 97kg).

    And yes, measure sag by tying a rubber band or zip tie round the fork stanchion so you can see how far it sinks when you sit on the bike.
Sign In or Register to comment.