had my deore’s for a year now from new,excellent brakes can’t fault them,but lately I’m finding I have to pump the lever a few times to gather some sort of braking pressure,it’s only on the back brake,front is not as good as it used to be but its ok,if it does need a bleed then where is best to buy the kits,I’m running a 160 rotor on the rear,would I benefit from running a 180,I’m going through pads like mad but I’m not hard on the brakes?

If it is pumping up then yes it needs a bleed, shimano are easy to do and bleed kit is about £25 from LBS.

Cheers wiggles,their not for the bin then…good to hear 🙂

Not exactly.. I think this is what is happening to your brakes: As the pad wears the caliper needs more fluid in it – this is pumped out of the reservior. The reservior is covered by a rubber diaphragm that has convolutions in it so that it can be sucked down into the reservoir as the fluid leaves it. So either your pads are worn enough that the diaphragm is stretched out near its limit, and will slowly draw fluid back out of the caliper – this only happens slowly which is why if you pump it quickly it works; or the small hole that lets air in behind the diaphragm to equalise pressure is blocked.

Bleeding will restore function because you’ll end up adding more fluid. But for a short term fix you can loosen the reservoir cap and let a little air in there. Just don’t operate the brakes when the bike’s upside down if you do that 🙂 Your pads are probably pretty worn yes?

If there’s bubbles in the line (which is why you’d normally bleed) the lever gets pushed out as your brakes heat up.. different thing.

Yes pads are worn,thanks for the info,I’ll try it but I’ll get a bleed kit anyway and bleed them,good to know for future reference.

Epic bleed solutions kit, and web page are a good starting point. Very clear instructions.
I find that with Shimano brakes once the pads are worn to a certain level you find the problems you’ve got.

Push the Pistons in the caliper back (I leave the old pads in and use a screwdriver between them) and pop in new pads. This might cure it. If not a bleed is really easy. Just take your time