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  1. #1
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    XT M785 2x10 chainring issues

    Hi, I'm having an issue with the large chainring on the XT 2x10 cranks on my Trance 27.5 When I'm in either of the largest two cogs on the ear the chain intermittently rides upon the teeth on the chainring, clatters about then drops back onto the chainring properly. It seems to happen on two particular teeth, either on behind the crank arm or one 180 degrees opposite, watching it on the stand I can see the tooth hit the side plate on the narrow links in the chain. I had something similar happen a while ago and found a bent tooth but this time they all look to be in alignment and Iíve checked the chainring with a straight edge to check it isnít bent. Is this a symptom of a worn chain on 2x10? itís just hit 1/16 stretched so I have a new one on order. Would a 1 or 2mm difference in chainline cause this?

  2. #2
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    Have you tried micro adjustments on the shifters to see if that helps? Maybe due to stretch on the cables?
    2011 Yeti 575 Enduro - full XT group, Thomson cockpit, and Chris King upgrade

  3. #3
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    Could be a stiff link in your chain, too. Try to see if it happens at the same spot on the chain rather than the same spot on the ring...

  4. #4
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    Is the chain rubbing the front derailleur in those gears? If so, MD_TX's suggestion seems best.

    Odd that it happens in only 2 spots...when you put the straight edge on the ring, did you check several different locations? All the bolts tight? I had a ring acting odd like this once and discovered I'd lost one. Put in a new one and all was good again.

  5. #5
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    Your front chain ring has some bent teeth. Look at it with the chain off and spin the crank.

  6. #6
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    When checking with the straight edge checked the whole ring except for the bit behind the cranks. The chain isn't hitting the derailleur so I don't think it's related to shifting adjustments. I'll check the chainring bolts but I haven't noticed any noise that normally goes with loose bolts. Teeth look like they are all where they are meant to be, the tooth 2 before where the chain lifts up is angled slightly inward but the corresponding tooth in the opposite position looks exactly the same so I assumed that was normal and helps with shifting in some way.

  7. #7
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    Quote Originally Posted by Anth08 View Post
    Is this a symptom of a worn chain on 2x10?
    A worn chain can definitely cause symptoms like that, I would replace and see how it goes.

  8. #8
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    Quote Originally Posted by Anth08 View Post
    When checking with the straight edge checked the whole ring except for the bit behind the cranks. The chain isn't hitting the derailleur so I don't think it's related to shifting adjustments. I'll check the chainring bolts but I haven't noticed any noise that normally goes with loose bolts. Teeth look like they are all where they are meant to be, the tooth 2 before where the chain lifts up is angled slightly inward but the corresponding tooth in the opposite position looks exactly the same so I assumed that was normal and helps with shifting in some way.
    If JBWeld says try the chain first, and it's already on the way that's likely and I've learned yet another thing from him. Can't rep again JB or I would.

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