Right this is gonna sound weird but here goes. Rcently bled rear brakes and rplaced pads. Lever felt spongy i thought the pads just needed to bed in, bike has had about 20hours riding since and lever still the same.

So of to the LBS i went and mech rebled but no air in the system, lever felt great with resevoir cap off so thought that was it. Put the resevoir cap on and brake back to a sponge we repeated the process several times with the same horrible lever sponge every time the rsevoir cap went on. What the hell is going on? Shaun (mech) has never seen this problem before.

I need HELP please!

Well, spongy brakes means that air IS in the system.

So somehow the top cap is introducing air though I'll admit I can't think how.

EDIT – only thing I can think of is that somehow the reservoir cap is allowing the brake lever piston to leak so that the whole reservoir is pressurised when pulling the brake lever.

i thought that too but no obvoius fluid leaks. In original post forgot to mention that the lever squeaks

The lid has a vent in it to allow the bellows to expand/contract with the fluid movement. Try cleaning between the bellow and the lid, or swap the lid from the front brake to prove the theory.

I don't think people are going to be able to help for this sort of problem without seeing it.

As I see it there are three options

– a leak or something flexing that shouldn't – no idea how this could be triggered by the cap unless something's bending/distorting when you do it up

– air in the system still though again, I don't see how the cap would have an effect

– somehow the top cap causing a problem with the seals in the lever piston meaning that pulling the lever is pressurising the reservoir which just flexes the rubber reservoir seal

I'd get it working without the cap again and then fit the reservoir cap but don't bolt it up – does it still work? If so then very gradually tighten the bolts and see when it stops working.

bike is sitting in the shop but will see if shaun is still in

bugger hes off have got in touch with hope so maybe they can help

You are "rolling" the rubber cap on to the top of the reservoir aren't you? If not, you risk trapping air in the top. Hope has got a vid on the site that shows how to do it.

i think that may be the problem i will check when the shop opens tommorrow

I think TrevorB is on the right track, if the diaphragm's movement is restricted due to a blocked vent then it'll effectively suck the fluid(and therefore the caliper pistons)back into their bores, giving you a long lever travel.(I haven't actually experienced this however, but the theory fits in with your problem nicely)