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  1. #1
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    Pop in Chain/Pedaling - 100% New Drive Train

    So here is my issue, I am a novice with bike maintenance, recently I repaired my entire drive train by putting a new cassette, chain, and all new front cogs. My drivetrain is 100% Shimano. Everything shifts like a champ, except when I am shifting gears with my rear derailuer, there will be a "pop" in the shifting giving me a moment of no pedal power and this typically causes me to lurch forward (painful). This happens typically when I am out of the saddle, but occasionally it even happens after I have shifted while I am just pedaling.

    Do you guys have any ideas of what I can do to fix it? Is it possible I didn't size the chain right and its too large? Other than this "pop" it shifts like a dream...

  2. #2
    ups and downs
    Reputation: rockyuphill's Avatar
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    What rear hub do you have, that sounds like a freehub skipping. There were some XT and XTR freehubs that had that problem because the grease was too sticky.
    I'm a member of NSMBA and IMBA Canada

  3. #3
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    Could be either over or under tensioned rear derailleur cable.

  4. #4
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    I've got a King rear hub, I had it reworked by King last year, so hopefully its still fine. I'll check the cable tension when I get home. Thanks guys...

  5. #5
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    could be the free hub body or the chain is the wrong one if its a 10 speed it matters which way it goes on some time or a stiff link

  6. #6
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    You really shouldn't be shifting while hammering out of the saddle. It puts a ton of stress on your drivetrain.

  7. #7
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    Quote Originally Posted by amtbr View Post
    This happens typically when I am out of the saddle
    Shifting under a heavy load will often cause the symptoms you're describing. If the hub was failing I'd suspect you'd see the skipping on a regular basis, not just during shifts.

  8. #8
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    Reputation: RustyIron's Avatar
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    You shouldn't shift under load.

  9. #9
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    While it's true you should try not to shift under load, it shouldn't be skipping like that. If cable adjustment doesn't work check for a stiff link.

  10. #10
    Diggity Dog
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    If the drivetrain is 10 speed Dyna-Sys make sure the chain is installed correctly. These chains are directional and the logo should go to the outside. 10 speed Shimano mountain and road chains are not interchangeable.

    Check the chain connecting pin. It should be flush with the outer plate.

    Make sure chain length is correct.

    Cassette lockring should be tight.

    Some hubs use a spacer on the inside that is installed before the cassette. If not installed the cassette will be loose no matter how tight the lockring is. Try to wiggle the cassette, if it moves try to determine whether it is the cassette on the freehub body or the freehub body itself.

  11. #11
    Tool
    Reputation: Pedalphile's Avatar
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    First things first - is the chain slipping on one of the rear cassette cogs or one of the front chain rings?

    I realize it may be hard for you to tell unless you have an observer to help, but you need to pin this down before you can solve the problem.

    It may be possible that your chain is too long. Visit the Park Tool site for chain length sizing instructions for your bike type.

    If the chain is too long, the rear derailleur will be unable to keep sufficient tension along the bottom of the chain. As you hit bumps or subject the drivetrain to vibration, such as a hard shift, the loose chain can actually whip itself off the chainring from the bottom, causing a skip or dropped chain.

    Do you ever get the problem when you stand and hammer on bumpy terrain without shifting, or does this only occur during rear shifting?

    Good luck,
    Pete
    I can barely get my mouth around it.

  12. #12
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    So I tried loosening the rear derailuer cable and tightening it and checking for stiff links and that didnt fix it. Today I noticed WHY its happening, when I shift "down" in the rear (from a larger cog to smaller > making pedaling harder) the chain jumps or gets whipped when it shifts and sometimes this seems to create that momentary gap when it misses the rear cogs. The chain never comes off and the shifting really isn't bad, its just this momentary period of disengagement that is driving me nuts. There is no clicking or anything, like its trying to grab, it just seems like the rear is flicking the chain too hard when shifting to smaller gears.

    Before I go messing around with the rear derailuer, can anyone point me in the direction of what is causing this problem and how to fix it? Thanks for the help so far guys...

  13. #13
    Tool
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    Quote Originally Posted by amtbr View Post
    Other than this "pop" it shifts like a dream...
    What does this mean? When does it 'pop' versus when does it not?

    I'm guessing that the skipping is occurring at the rear, but I don't think you've said so.

    Is your chain the right length?

    Is the b-screw set properly on your derailleur? You can find the details for determining this on the Park site.

    Is your rear shifter cable and housing new? If they're old (or if they've been thru some harsh conditions), they may be the culprit.
    I can barely get my mouth around it.

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