hydrolic disk brakes

[gasinayr]

havn't used my trek mountain bike for a while got it out yesterday and found that the rear brake was locked on and the level was solid. Had to open bleed nipple on lever to release some fluid for it to release. Seems like the fluid had expanded while sitting

 

[Drago]

With some systems this can happen in warm weather, particularly if the fluid is a bit old and tired, ie, absorbing H2O from the atmosphere. It seems that DOT fluid systems are more prone than those that use mineral oil.

 

[si_c]

Pretty much what @Drago said, time for a full bleed I think, worth checking to make sure that the pistons retract fully into the caliper as well before you go ahead and do the bleed.

 

[gasinayr]

Fairly new brakes and fluid so dont think a full bleed required, after draining a small amount off they seem to be working fine. I'll see what they are like when the colder weather returns. (next week likely )