UKC

Hi.
Need some ukc advice before I trawl the Internet.

Have a relatively new trek superfly hard tail. Has shimano kit and disc brakes.

Last time I used it back brake was razor sharp but made a bit of noise when used hard. Mid pitch shriek I'd call it.

Used it again last weekend and the noise is now louder and rear braking in now nearly non existent. It'll stop but I can't get the back wheel to lock.

I did give the bike a good clean a few weeks ago but was very careful not to get anything on the discs or anywhere near the pads.

If I have covered something I shouldn't have in something I should not what do I need to do to remove it?
Thanks
Darren

In reply to Run_Ross_Run:

check that both pistons are moving freely

In reply to Run_Ross_Run:

Take it it actually has pads in it? Wouldn't be the first time a bike got put together and the pads left out - I was in a bike shop only a fortnight ago where this had happened.

Possible a set of faulty pads might have disintegrated already?

Any obvious scoring on the disks? Can you see the pads moving through the caliper when you pull the lever?

In reply to Run_Ross_Run:

Sounds like they are contaminated, best way is to cook them.
I put them on the hob to get them nice and hot and it should strip the contamination out.
Plenty of help here
http://forums.mtbr.com/brake-time/contaminated-brake-pads-how-i-fixed-home-...

In reply to Run_Ross_Run:

Are the brakes Shimano XTR hydraulic disc brakes?
I had that problem with those brakes as well, on the rear brake after a period of non use. I bought them and used them a few times, then the problem started once I came back to ride it. The brake has come back to normal now after just repeatedly using the back brake as much as possible.

In reply to Run_Ross_Run:

Also turn on the extractor and open the windows it can get a bit fumy.

In reply to Run_Ross_Run:

I've found that once this happens the best bet is just to replace the pads... not very helpful I know, but effective when you get fed up with trying to fix them. It's possible that they are cheapo pads and have simply worn out - seems unlikely on a bike of that quality, but you never know. A friend of mine wore out the pads on a Carrera Vulcan (Halfords "not actually that bad" brand) in a couple of rides.

I've found EBC pads are good and last well if you end up replacing.

In reply to Run_Ross_Run:

Had a long running problem with deore caliper leaking onto pads. It was kind of obvious (same symptoms as yours, problem reoccurring after cleaning rotors, replacing pads etc) but bike shop insisted the contamination was self inflicted and tried their own remedies 1st (and 2nd... and 3rd!). Eventually they looked at the caliper, which, as I suspected, was the cause. To be fair to them, they replaced said caliper FOC, but frustrating to ride an unreliable bike for so long before being fixed.

Just switched to Nukeproof pads btw- they are great!