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Discussion Starter · #1 ·
I have a diamondback XSL with a recently replaced Deore lx rear derailluer. The chain length is ok and the frame isn't tweaked. It shift smoothly through all 9 gears.

When I am pedalling moderately hard sometimes the chain skips, enough times to be a severe problem and an annoying one. It's not jumping out of gear, it just makes a "clinggg" I can't really tell if it's trying to jump up or down a gear, though it never has.

So I don't know where I should look to fix this one. I'm thinking the chain links could be not not aligning properly on the sprocket teeth and then slamming back to where they are supposed to seat.

I want to know some usual problems that could cause this so I can look them over.

thanks
 

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Stiff Link?

Did you "break" the chain to install the new derailuer (common with Shimano chains)? Your description sounds like you have a stiff link, which is common when you re-connect a Shimano chain. This will cause a slight "skip" as the stiff link goes through the derailuer pullys and the cassette. Look closely while you backpedal your chain and you will see it.
To remedy, grasp the chain on both sides of the stiff link and flex it sideways back and forth a couple of times...this will usually take care of the problem.

Good Luck
 

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Is the derailleur skipping to harder or easier gears (ie: down the cogs or up)? If it's skipping down (to the harder cogs), you could try to increase cable tension by using the barrel adjuster on the rear derailleur - quarter turn at a time.
 

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This is common of Full Suspension

sonicsuby said:
Is the derailleur skipping to harder or easier gears (ie: down the cogs or up)? If it's skipping down (to the harder cogs), you could try to increase cable tension by using the barrel adjuster on the rear derailleur - quarter turn at a time.
This is a good idea, full suspension bikes will shift perfectly in a stand then skip when riding because the housing is flexing. They seem to need a little extra cable tension to aleviate this problem.
:thumbsup:
 

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I had the same problem last week. Check to make the derailleur is aligned properly by sighting down the chain and the bottom pulley is even with the cogs and chain. Also, you might need a slight r.derailleur tweak, that's what did it for me. check utahmountainbiking.com/fix for more
 

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Did you replace it w/ a new or used derailleur? If it is used, the pulleys may be worn out. This will cause the chain to slide to one side or the other on the pulley and in turn, slightly to one side or the other of the cog. This can cause it to skip, and then fall back into line.
 

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First off I would check for a stiff chain link like someone suggested. If that is not the case, then to me it sounds like worn chain or/and cassette (rear gears). See if the LBS will throw a chain checker on your chain to see if it needs replacement. If it is stretched enough to replace (0.75%) a new chain may be all you need. If it is stretched further, the chain may have worn the cassette down as well so you'll be replacing it, too. Is it skipping in any gear or only certain gears? If only certain gears, are they your most used gears? If so, that would also suggest the cassette. Skipping like you describe can also happen at the chain rings (the front gears) and is fixed by replacing the offending chain ring.
 

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Discussion Starter · #10 ·
I let out some cable slack and it fixed the problem right up. On the stand it's close to upshifting, but when I ride it there's no problem.

I took all the preload out of the spring and moved the suspension up and down and saw how much the suspension movement changes the cable length, it's significant.

Thanks for the help
 

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if none of the mechanical suggestions here work (and they're all good!), or even if they do work, keep the chain lubed; a dry or gunked chain will skip, too. i went through a flooded street (just barely missed "washing" the hubs) on the way home from work one day; HMX's screamed for three days, rear de puked on me, and the chain got arthritic, clanked and skipped all over the place. CLEAN AND LUBE....
 
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