I have had my bike hanging up unused for a few months now 😳 and I have taken it down to give it a run tonight and the brake lever isn’t returning. It was hanging up by the rear wheel and it’s the rear brake that isn’t working. The front brake lever is returning back out from the master cylinder but the rear sticks and in turn the brake binds.
What’s happened? I’ve just bled the system to no avail 🙁

Is it Hope? Mine is doing the same and I need to get round to fixing it…

Either the return spring is knackered (they sometimes rot away to nothing) or the pistons are sticking (wrecked seals/filthy pistons/combination of the two). Lever piston seals are also a possible cause, though less likely. All of this assumes that you’ve bled them properly, of course, and that the fluid is in good condition.

Formula ORO. I remember my wife’s Avids did something similar.
Is it the hanging that the brakes don’t like? Should I flip them every so often?

It’s not something daft is it, like dry lever pivots? thats what mine was (Hope M4′)

If its hope, just spray it liberally with GT85 and work it back & forth. It’ll soon free up

I think it’s a bit more than that but I’ll go and spray a bit more

Old oros had an issue with the plastic piston in the master cylinder swelling when not used for long periods. This happened to my brake and it was fixed under warranty. The later ones used a different material.

Be careful what you spray liberally, some are mineral based and will swell your seals, causing even more problems.