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  1. #1
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    Chain skips off cassette

    so the chain keeps skipping off the cassette and recatching when I exert a certain amount of force on the drivetrain. Took it to the LBS and had them adjust the rd to make sure it is aligned and explained the problem with the tranny. Still skips and is frustrating. I think it could be the casette. It is a cheap 9sp forte that I stashed away for an emergency. Used it to throw on the new xt rd and shifters to try'em out. Has anyone had this and what did you do to remedy the situation?

  2. #2
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by squash00
    so the chain keeps skipping off the cassette and recatching when I exert a certain amount of force on the drivetrain. Took it to the LBS and had them adjust the rd to make sure it is aligned and explained the problem with the tranny. Still skips and is frustrating. I think it could be the casette. It is a cheap 9sp forte that I stashed away for an emergency. Used it to throw on the new xt rd and shifters to try'em out. Has anyone had this and what did you do to remedy the situation?
    The chain and/or cassette is worn out. Replace both, and maybe the chainrings.
    mtbtires.com
    The trouble with common sense is it is no longer common

  3. #3
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    both are new is the problem.

  4. #4
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by squash00
    both are new is the problem.
    Still say replace the cassette and chain. You are not using an 8-speed chain, are you?
    mtbtires.com
    The trouble with common sense is it is no longer common

  5. #5
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    Try to be more specific in describing exactly what's happening..

    Is the chain dis-engaging at high torque and skipping across the tops of the teeth, or is it trying to auto-shift to the adjacent cog?

    Also , does this happen on all cogs, or only certain ones?

    Exactly what brand/model chain and cassette,.

    More details will help us pinpoint the potential causes.
    fb
    www.chain-L.com

    The key to solving any problem is to understand and address the underlying cause.

  6. #6
    Bicyclochondriac.
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    Quote Originally Posted by FBinNY
    Is the chain dis-engaging at high torque and skipping across the tops of the teeth, or is it trying to auto-shift to the adjacent cog?
    I think this is what is often happening when people think it is skipping.

  7. #7
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    Quote Originally Posted by kapusta
    I think this is what is often happening when people think it is skipping.
    Probably in this case at least, since it's a new chain and cassette. But it would help if posters were more clear since the causes and remedies for ghost shifting are totally different from those for climbing out under load.
    fb
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    The key to solving any problem is to understand and address the underlying cause.

  8. #8
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    Sorry about the info, should have included more. The chain is skipping across the tops of the teeth when under torque. It isn't shifting to another gear since it always engages the correct gear everytime. Plus, this is why I took it to the LBS to correct any auto-shifting isues. It is under high torque when I come out of the saddle to push. The chain releases and I bottom out the pedal and it catches since torque is gone. The chain is a 9 speed chain Shimano Dura Ace that works wth the XT, The cassette is a cheap 9sp forte from performance that is suppose to work with 9sp, that as mentioned I had stashed away for emergency's. This isn't really an emergency but I want to ride. I am just trying to diagnose if the cassette is useless and I need to replace or if it is something else. For all I know everything is suppose to work but the problem remains. I was hoping on purchasing a new cassette but I think this is the issue. Hoping someone can confirm this.

  9. #9
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    Thanks for the info, it sounds like maybe it is just an adjustment thing. Could you pass on a little more about the "B" screw. I thought I adjusted it correctly when I installed the RD but it sounds like maybe I didn't. I guess the questions is what does it do exactly. Would changing the chain length do anything? Should I shorten or maybe add another link. I am really into to fixing things myself and am looking for every opportunity to learn how to fix or adjust settings to make the bike run smoother. I am hoping this pays off when I start building my own bike.

  10. #10
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    Squash- Usually that skipping is caused by using a new chain with an old cassette. Since both are new, we need to review other possibilities.

    If it only happens on one cog, look for a burr or deformed tooth.

    If it happens on all the smaller cogs, it might be lack of chain wrap. Adjust the "B" screw to move the RD forward slightly, being careful to check that it still properly clears the larger cogs.

    It could also be a slightly off line hanger that feeds the chain at a less than ideal angle for smooth engagement.

    It could be that a crap cassette's tooth profile is such that a chain with limited bellmouth on the inner plates can hang on top of the tooth, and not slide down smoothly.

    Lastly, it could be a lubrication problem, (not being self-serving here). A poorly lubed or slightly stiff chain can hang and not wind smoothly onto small cogs causing the skip, It doesn't have to be a visibly stiff link, just less than fully supple. If you're using a wax or dry lube, try an oil based wet lube, before unnecessarily trashing the cassette.
    fb
    www.chain-L.com

    The key to solving any problem is to understand and address the underlying cause.

  11. #11
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    In my experience, chain skipping issues have ALWAYS been due to worn out rings on the crankset. And there have been at least two occasions when I replaced the cassette and it didn't solve the problem. With a new cassette and new chain, I'd be 95% certain that the skipping is occurring on the chainrings and not the cassette. Chainrings are usually aluminum and wear faster than the steel sprockets on the cassette. And if you just put on a new chain, it's very prone to cause just this problem.

    It's quite difficult to determine whether skipping occurs on the front or back - I've never been able to tell by looking. But the problem was always solved by new chainrings to go with the new chain.

    Bent sprocket teeth could do something similar, but unlikely if it's brand new.

  12. #12
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    Thank you for all the suggestions. My crankset is older but it still locks in the chain well and I haven't had problems with it skipping from there but it is most definitely skipping in the rear. I will check the link out and do some adjusting and see if this fixes it. Hopefully, teaching school goes by fast today and I can get home quick.

  13. #13
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    Quote Originally Posted by kgginslc
    In my experience, chain skipping issues have ALWAYS been due to worn out rings on the crankset
    With all due respect, your experience must be fairly limited because nothing in life is ALWAYS caused by only one thing. BTW- later on you list alternate possibilities, belying your opening sentance

    Quote Originally Posted by squash00
    Could you pass on a little more about the "B" screw. .
    The "B" screw sets the angle of the RD ro the hanger. It's a mattter of staying as close to the cassette w/o getting so close as to have problems on larger cogs. Changing chain length also affects chain wrap around the cogs.

    Here's a link to "B" screw info, on a usefull site to someone wanting to learn more about DIY bike repair.
    http://bicycletutor.com/adjust-rear-derailleur/

    good luck.
    fb
    www.chain-L.com

    The key to solving any problem is to understand and address the underlying cause.

  14. #14
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    Please forgive me ... I hope to live up to your standards in the future.

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