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  1. #1
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    Chain suck only in small ring?

    I installed a new rear derailleur (Sram x-7) replacing a X-7 but now have chain suck, but only in the small chain ring (3x9) and only when climbing. The only difference is the new one is a med. cage and the old was long. Everything was fine before, but wondering, is the chain too short or long? It looks like the chain just quits rolling through and the cage is pulled toward the crank set (at least that is what I see before un-clipping and trying not to fall over) I can not make it happen with the bike on the stand.... thoughts? help!

  2. #2
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    Did you shorten the chain? Just curious, but I don't think this would matter.

    The only thing that was preventing the chain suck prior to the new derailleur was the angle of the chain releasing from the small chain ring. Now your chain is on the small chainring longer and when only under stress (when climbing), your chain cannot release from the small chainring b/c of the small hook/shark fin profile your chainring teeth have worn down to. You could try to file the tips of the chainring teeth to remove this 'hook' from keeping your chain on the chainring.

    Also, make sure your chain is properly lubed.

  3. #3
    Trail Tire TV on blogger
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    you probably need to shorten the chain.. a long cage take up more chain length that a mid... guessing it was too long in the first place and the derailleur had enough overlap to take care of it. Also your front rings or even the chain may be damaged/worn. A mid cage derailleur has less flex than a long in the cage and it could be just enough to cause the issue to stand out.
    Going to try and bring Trail Tire TV back. go take a look... http://trailtiretv.blogspot.com/

  4. #4
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    Thanks - new chain too.

    I forgot to add, I did install a new chain when I replaced the derailleur. I just got back from a ride and it is still doing it. I will try to re-size the chain using instructions here and check for "sharks teeth look" on the chain ring. I am new to setting up drive trains, but the nearest LBS is 40 minutes away.

  5. #5
    Trail Tire TV on blogger
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    with the new chain added I can almost 100% say you're chain ring is worn...

    to verify, just slap the old chain back on.. if it goes away your drive train is worn and you really need to replace the whole thing... Cassette, chain, front rings.
    Going to try and bring Trail Tire TV back. go take a look... http://trailtiretv.blogspot.com/

  6. #6
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    Re: Chain suck only in small ring?

    Quote Originally Posted by thomllama View Post
    with the new chain added I can almost 100% say you're chain ring is worn...

    to verify, just slap the old chain back on.. if it goes away your drive train is worn and you really need to replace the whole thing... Cassette, chain, front rings.
    You have a sucky chain.

    Ok, up above is more than likely your problem.

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