help rear derailer adj

[hfxgearhead]

Help me with my infernal indexed deore xt
i have been trying to adj the rear derailler, with not much success. i am totally inexperienced with index adj.

Symptoms: shifting gears causes, chain slipping off and sometimes getting caught/jammed, no shift untill several clicks or jumping cogs, cannot put pressure(stand) on peddals in middle gears. wimpy gears are most stable. Most unfortunate is 'spontanious shifting' lol.

Diagnosis? Do i need new cable? New chain? Proper adj?

tx for any info,
grumpy in hfx

[JerseyDevil]

Ahhhh.... a Jedi in training!
You could have one problem or a couple there. This is one of those hard to diagnose over the 'net things.
Are you a good customer of a local shop? If so, have them fix the problem, and then ask what it was. Most times, they'll tell you what they did. You'll know what to look for next time. If you get one of the friendlier mechanics alone, he might even show you how to fix it if you play your cards right.
Otherwise, suffer the burdon of the learning experience. Get a bike maintanence book or the "Break it, fix it, ride it" CD-ROM.
May the force be with you.

[Rotifer]

Jersey, of course, is right. Another suggestion ... I had a similar problem but decided it was the derailleur. If you decide to adjust it yourself use the instructions provided at www.parktool.com - great resource.

[hfxgearhead]

TX for the quick replies. I think I am gonna mess with it somemore and do more research online then take the walk to the bike shop tomorrow.

It may be a componentry issue... I am currently running it with DEore xt FD and RD, LX crank and spider and a Acera rear hub with hyperglide-c cassette... are these compatable? cuz i have a sinking feeling they are not.. also.. i am missing a screw from the RD. Not an adj screw either.

i love the parktool site as well as sheldonbrown.com

Cheers!

[Ken Braatz]

This is assuming that your chain line is ok, the components are clean and properly lubed and that they are compatable and in working order....

Use your High/Low limit screws only to adjust the the point at which the chain stops on the cassette. If the chain shifts off of the cassette in either direction or if it won't shift into a gear (typically, the largest) then use the limit screws. Once you have them set, LockTite them and leave them be.

The barrel adjuster is where you set the shifting. Get it to a point where it shifts ok then ride for a bit, working through the gears. Adjust 1/4 turn, ride some more then repeat the process until you have it dialed in. This could take a while. Remember, also, that the shifting will be different under load than it is on a workstand or upside down.

The gears slipping could be a worn cog and/or chain. If you have the rear der dialed in under a flat road load and it's still slipping/skipping, my guess is that it's a worn cog/chain issue. If that is the case, check your chain rings for wear and replace them (if needed) and the rear cassette and chain. Don't replace the cassette without replacing the chain.

The missing screw is worrisome.

Also, you will probably never get perfect, quite and buttery shifting in all gears on all chain rings -- usually one or two gears will be a bit slower to shift or will rub a bit, just make sure they're gears you don't use often.

If all else fails, visit the lbs.