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Thread: Chain Skipping

  1. #1
    lag
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    Chain Skipping

    My chain is jumping a bit on the rear cog and that can piss you off as you all may know.

    It ONLY happens when I am hammering up a short section of trail, only when I am out of the saddle, only when I am fully suspending the bike up a short steep.

    I am a fairly good bike tuner. The rear cog is sort of new, the chain is sort of new, all the cables and such are sort of new. In fact, last season this started so I replaced the cog, chain and cables thinking this would do it.

    I ride a SC Blur. Any suggestions? I have tuned the barrel adjuster back and forth to both ends and everywhere in between.

    Could it be the SC Blur frame in need of new bearings? Derailer gone bad? Has anyone ever had this problem?

    Thanks in advance.

    lag

  2. #2
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    are you running full length casing on the derailleur cable? I had the same problem on my enduro - turned out that one of the sections of cable housing was too short, so when the suspension was compressed the cable was pulling and shifting gear. THis was sorted out by putting a full length cable housing on, with plenty of slack.

  3. #3
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    Housing is a possible...

    I had two similiar problems. One was caused by a short housing. Happened then only when the suspension compresed. IMHO the housing was worked by the suspension and caused extra tension on the cable. Also took the finish of the seat stays.

    Second was cause by a broken housing close to the rear derailleur. Asn't obvious to me up until I actually saw the metal shining through close to the end cap.

  4. #4
    locked - time out
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    How olds the chain? Also what condition is the trans?

  5. #5
    lag
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    All... Thanks for the replies.

    The entire drivetrain is pretty new (last season before the snow).

    The housing is not complete throughout; the middle section is bare cable. I wonder now if that is the issue. Thanks for the potential solution. The housing doesn't appear to have any breaks in it either.

    Bent hanger? Break down and take it into the shop? (prefer not to do that)

    Any other possible areas on the bike to look into is MUCH appreciated.

    kindly,
    lag

  6. #6
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    There could be several issues. As mentioned before, the cable and housing can get old pretty quick, but you should be able to quickly eliminate that problem with a few minutes of troubleshooting. What gear does this happen in?

    If its 'all' gears, then a stretched chain and worn cassette could be problem. I could also be the chain ring in front your're using. Although you've said you've eliminated these from the possible range of issues, your paw's might be going out in your freehub body. What Hub do you have?

    I encountered a loose cassette body on a bike yesterday, same range of problems. We'll have to replace the hub.

    Also, check to see if your cassette rings are not bent (same for the front rings as well).

  7. #7
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    Quote Originally Posted by lag
    All... Thanks for the replies.

    The entire drivetrain is pretty new (last season before the snow).

    The housing is not complete throughout; the middle section is bare cable. I wonder now if that is the issue. Thanks for the potential solution. The housing doesn't appear to have any breaks in it either.

    Bent hanger? Break down and take it into the shop? (prefer not to do that)

    Any other possible areas on the bike to look into is MUCH appreciated.

    kindly,
    lag
    If you refuse to use a shop, stop by my place and we can take a look at it. I have a blur and am fairly good at drive train troubleshooting. PM me if you're interested.

  8. #8
    I think I can.
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    Possibility

    I ride the SC LT and had the same problem, checked derailer hanger, replace chain, rear cog, front rings, rear derailer and checked and cleaned all cables, also checked and tighted all bolts on pivot mounts, think that was it.
    After all was done got back on the bike and still had the same problem who hear can tell me how I fixed the problem.

    By the way the problem was severe chain skip under load and only happened when I was climbing or putting severe stress on the drive chain.

    kchri can not answer this puzzle as he knows how I fixed it

    Dam,
    Bikes are FUN

  9. #9
    Your retarded
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    Quote Originally Posted by JOEMTBR COLORADO
    After all was done got back on the bike and still had the same problem who hear can tell me how I fixed the problem.
    Magic?
    A trail thatís too difficult wouldnít exist because itíd never be used. But, trails can exist thatíre too difficult for you.

  10. #10
    e-misanthrope
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    This probably isn't the issue if you've swapped the chain, but have you checked to make sure you don't have a stiff link in there? Where the chain and the cassette "slightly used" together? - or were they on different bikes and then put together on a newer bike?

  11. #11
    Inflexable...
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    Great. I can actually answer a question and I am not allowed to...
    Tact is for people not witty enough to be sarcastic...

  12. #12
    I think I can.
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    Quote Originally Posted by lagarto grande
    This probably isn't the issue if you've swapped the chain, but have you checked to make sure you don't have a stiff link in there? Where the chain and the cassette "slightly used" together? - or were they on different bikes and then put together on a newer bike?
    All the parts are brand new xt or better, also rear hub is less than 6 months old, perfect condition.

    Dam,
    Bikes are FUN

  13. #13
    Your retarded
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    Bad bearings in the linkages? A little bit of bearing slop would go a long way in terms of chainline. That's my real guess. I was just throwing out magic because kchri was involved.
    A trail thatís too difficult wouldnít exist because itíd never be used. But, trails can exist thatíre too difficult for you.

  14. #14
    rr
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    Your hanger was out of alignment on that last ride, and your rear hub was almost frozen, did you fix those things?

  15. #15
    I think I can.
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    Yes rick I fixed all the above, the actual problem was my spokes were not tight enough and the hub assembly was twisting under the presure causing the skip. Once I tightened the spokes and trued the rim the problem was solved.

    Thanks for playing all.

    Look forward to riding again tomorrow.

    Dam,
    Bikes are FUN

  16. #16
    e-misanthrope
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    Quote Originally Posted by JOEMTBR COLORADO
    Yes rick I fixed all the above, the actual problem was my spokes were not tight enough and the hub assembly was twisting under the presure causing the skip. Once I tightened the spokes and trued the rim the problem was solved.

    Thanks for playing all.

    Look forward to riding again tomorrow.
    Not trying to troll or anything, but this doesn't make sense - wheel tension should have zero effect on your drivetrain function, provided your tire isn't hitting the chain or anything.

  17. #17
    Your retarded
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    Quote Originally Posted by lagarto grande
    Not trying to troll or anything, but this doesn't make sense - wheel tension should have zero effect on your drivetrain function, provided your tire isn't hitting the chain or anything.
    Pffftt.... Troll.



    I agree with the lizard guy. That doesn't make a whole lotta sense.
    A trail thatís too difficult wouldnít exist because itíd never be used. But, trails can exist thatíre too difficult for you.

  18. #18
    rr
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    The hub/cassette in relation to the der should not change with loose spokes, the hub is bolted firmly to the frame, I guess the rim could move around some. If you were riding your wheel with spokes that loose you might want to have a shop do a rebuild, you probably over stressed the spokes and they could start breaking on ya.

  19. #19
    I think I can.
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    Makes perfect sense when you think about it, if the hub is staying trued to center under load from the torque the drive train, if the spokes are loose this will cause the hub to turn ever so slighly under load which was all it needed to cause a skip or the chain to hop out of gear.

    I worked this problem one problem at a time and rode the bike after each repair, to say this was the only cause I would have to say I can't prove it but after tightening the spokes and straightening the rim the problem is gone. That is enough proof for me.


    Quote Originally Posted by lagarto grande
    Not trying to troll or anything, but this doesn't make sense - wheel tension should have zero effect on your drivetrain function, provided your tire isn't hitting the chain or anything.

    Dam,
    Bikes are FUN

  20. #20
    e-misanthrope
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    Quote Originally Posted by JOEMTBR COLORADO
    Makes perfect sense when you think about it, if the hub is staying trued to center under load from the torque the drive train, if the spokes are loose this will cause the hub to turn ever so slighly under load which was all it needed to cause a skip or the chain to hop out of gear.

    I worked this problem one problem at a time and rode the bike after each repair, to say this was the only cause I would have to say I can't prove it but after tightening the spokes and straightening the rim the problem is gone. That is enough proof for me.


    It just doesn't make sense because the spokes do not keep the hub centered, the axle does.

    I guess if your bike is working, that's all that matters.

  21. #21
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    Here is a different take on the issue.

    In my experience skipping under load is 90% of the time a worn FRONT chainring. Usually the middle goes first, but sometimes it's the small. Try the same climb in both the middle and the small, if only one is bad, it won't skip on the other.

    It may feel like a rear cog, but it's rare to wear down any of those but the 2 smallest.

    The other 10% of the time it's stiff link in the chain. Spin the cranks backwords and watch for a hop over the pulleys when the stiff link comes around

  22. #22
    how heavy are you ??
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    doubt it ...

    but there is some space between shimano cassettes and non shimano hubs that might be helping this along.... gotta get the spacers to make the cassette solid on freehub body
    Scott

  23. #23
    lag
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    Thanks again for all the chatter on this.

    The loose spokes / untrue rim solution is wild. I did try to tighten a few spokes last season, causing the rim to wobble; essentially messing with something I shouldnt have. After a couple of hours and couple of beers, the rim is somewhat true. Getting the rim trued by a professional WILL be the next move. I must try this, will post back the results.

    Hub is Chris King. (to answer a question above) Replaced the housing / cable last night and made it as long as possible to prevent stress under load. Cassette is Sram, chain is Sram, up front is XTR and a bit worn, derailer is XTR.

    Again, thanks to ALL for the chatter on this; it is always great to ask questions here!

  24. #24
    I think I can.
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    So what did you figure out, did you find the problem????

    Dam,
    Bikes are FUN

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