I have had a XT rear mech for 2 months or so - very smooth, better than LX, esp with new XT rapid fires...(old style) all very easy, very efficent etc...etc...

Then one day it all went very badly wrong...no crash, no big freeze (but admittedly a lot of peak mud)... my new kit stopped working...

I am pretty au fait with rear mech indexing, and this time i'm totally at a loss.

the mech changes to an easier gear like it used to, perfect..

but to change to a higher gear is A NIGHTMARE, have to spin the wheels for ages before (if ever) it changes...then i get pissed off and flick the rapidfire again...and it changes up twice!!! arrrgggh...!!!

i have wd40ed the cables, cleaned the mech ( a lot), sprayed random doses of degreaser in to the rapidfires all to no avail..

when i try to change to the higher gear the cable doesnt seem to move.

I've tightened (anti clockwise anyway) the cable tensioner on the mech.... no joy, if i do it too far then it just starts skipping the chain about in a random type manner...

err.....

anyone got any suggestions????

Sounds like a cable outer problem.
Replace the outers and try again.

yeah your cables/outers are f*cked to my way of thinking. Just spraying lube in wont clear them or help if there is a big problem and I think it can just help degrade the liners even more.

Bent your gear hanger? I spent ages trying to tune my gears but ended up taking it in to my LBS for a service. On the printout 4 days later: 'straightened gear hanger...'

Felt stupid, but shifting is smooth now. Am happy.

nice one, will give it a go!!!!

is the cable tightened the wrong way up on the mech. i did this, spent hours trying to get it right but couldnt do it so took it to my local bike shop and they did it in 2 minutes, and they charged me a fiver!!!!:o(
o yeh your4 rear mech might hav 2 much lateral movement in the cage test by grabbing the cage and wobbling from side 2 side, if this is the case u need a new rear mech

I had loads of trouble with the old LX on my Whyte. It turned out to be the cage. It had twisted above the lower jockey wheel. I was under the impression the hanger is supposed to go first