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  1. #1
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    Chain drops at weird times

    Greetings! I am having an issue with my chain- it occasionally comes off or skips when I crank really hard or step off quickly in the middle of a tricky section. It always derails towards the frame- onto the bottom bracket. I am about 200 lbs. and have always been tough on equipment.

    From the searches I did people recommend checking chain tension or using a chain guide. The tension on the chain should be ok- I did the big-big + 2 links method like always. I'm reluctant to use a chain guide since I run a 22-32-bash and use all those gears.

    Could it be an issue with chainline? It usually happens when I'm in the 3rd from largest cog (24t) and the 22 front chainring. Would it be worth removing the smallest cog and putting a spacer on the other side of the cassette?

    Specfics:
    2006 Giant Trance 22"
    BB: Truvativ Gigapipe SL
    Crankset: TruVativ Hussefelt ISIS
    Chain: SRAM 971
    Cassette: SRAM 11-34

    The bottom bracket, crankset, chain, and cassette are all less than 5 weeks old. Any help you could give me would be great!

  2. #2
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    bump

    C'mon- nobody has any ideas at all? Anything???

  3. #3
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    check your low limit setting on the front D. I recently changed from a triple to a 26/36/bash and had a finicky front D that took a bit to set up correctly. I am set up with about a 1/4 turn past where the chain rubs in lowest rear (big 34) and front 26. It took a while to adjust where I got good shifting but I have not yet dropped the chain.

    I weigh about 220-225 w/gear and ride a Heckler.

  4. #4
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    Check for bent teeth, bent chainring. Eye ball fron the rear and top while pedalling slowly on the workstand. Check also for bent cassette teetn etc. Check for worn hub (cassette wobble)

    Probably not chain line.

  5. #5
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    new2this-
    Today I adjusted the lower limit screw as you suggested and didn't have any drops, so maybe that was it. I also rode a different trail than normal so I'm not going to claim complete success until I can ride my normal route.

    jeffscott-
    I've checked the teeth and chainrings and everything looks fine. I'll look into the cassette wobble tomorrow if I have time, thanks for the lead.

    This problem seems to be on the mend, but in return my chain now started skipping across the rear cassette under more moderate loads. Makes me wonder if cassette wobble is the culprit.

    Thanks again for the help, if you have any other ideas I'd be happy to hear them. I'll post back soon with an update.

  6. #6
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    No cassette wobble could be found. I moved the cassette further outboard slightly using a small spacer. I also dropped the front D down slightly, I had it in the original position from when I ran a triple. Seems better so far, if I have any other insights I'll post again for anyone who has the same sort of issue.
    Thanks!

  7. #7
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    Check your chain. Especially if it is skipping on a regular basis. If you kinked a link it will cause a skip. Find and remove the bent link and your back up and running. But if you kinked one link you probably need to replace the chain.

  8. #8
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    Thanks for the advice, but I checked it earlier today and it was fine. Good idea though.

  9. #9
    Rod
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    There's definitely a reason that your chain is skipping. That doesn't make any sense. That happened to me when I put a new chain on a worm cassette. That is definitely not your problem since you replaced everything 5 weeks ago. It has me puzzled. Post back here when you do or don't find what's causing the chain skipping. I've never had chain skip, except for my one example above, or have heard of it unless something is bent.

  10. #10
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    hmm.....Im having the same trouble. Middle ring to bottom and jamming the cranks. Have not solved it as it is not happening much, but did happen a few weeks back in the middle of the night during a 24hr event.

    Under discussion was the condition of the chain wheels. They have 4500km on them and chain #2 went on about 800km ago. They are now showing asymmetric teeth so are warn. Anyway this was the conclusion for my problem, that the drive train is worn.

    But you have new all drivetrain then ? Two suggestions the SRAM chains are a bit stretchy so check yours is not too long now. I have see these grow even after 200 km. (IMHO shimano better chains by a good measure) Second possibility is your chain rings may have a particular orientation that means it could be rotated about the axle by 90 degrees. Sounds obvious but I made this error once.

  11. #11
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    I rode today and the chain skip was completely gone. Not just intermittent, but utterly banished. I didn't change out any components, just lowered the front D, adjusted the limit screw, and moved the cassette further outboard with that small spacer. I am amazed that it worked, I figured that there was something bigger. Anyways, thanks for all the advice. Good luck to all of you!

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