Just fitted a Hope M4 brakes; front is fine but the rear has all 4 pistons sitting out a little, enough to be in contact with the disc.

Trying to push them back inevitably results in the others coming out further etc – bored now with chasing them all round, do I need to let a little fluid out? (They all seem to move OK by the way).

I had a similar sounding problem and found that following the videos below sorted it right out.

Set up a caliper Video

Centralise caliper pistons Video

Thanks Paulio, that's h a helpful video, but my problem is that all the psitons are so far out that I have to really push the rotor between the pads just to get it in. And none want to move back……

what I do when this happens is I take the pads out and put a tiny drop of silicon lube on the piston and let the capilary action pull it around. Then ease the pistons back in do it just lubes the seals slightly. Might need doing a few times but this will ease things.

Did you have to pump the lever up when you first fitted them? If so, it's not going to be a case of too much fluid. The spring in the master cylinder extends that piston which will cause the 4 slave pistons to get "sucked" back. If this isn't happening, it's probably just that the seals are a bit dry and sticky. That's the down side of 4 pots, there's more circumference to drag for a given piston area.

Loosen the reservoir cap a touch and push them all back together, you can also do this by opening the bleed nipple but risk drawing air into the caliper when the pistons relax.

Thanks chaps.

They came like it (second-hand buy off the classifieds), I'm using a Hope rotor that I had knocking around, which I'm guessing is just a tad thicker than the previous one used.

Thanks for the tips.