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Thread: Chain skip

  1. #1
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    Chain skip

    So I've done some searching and still no success.

    I have chain skip when pedaling hard uphill or jumping up over obstacles. no fun.

    Riding a Specialized FSR xc ('06 I think). Deore LX rear derailleur.

    So I read up and decided to replace my cassette and chain and bought SRAM 971 chain and 970 casette. I think this should be compatible with the 9 speed Shimano cassette that was on there to begin with (I believe the stock chain was a 950 or something)

    Still skips.

    Made sure the rear derailleur is shifting smoothly, to no avail. (cleaned and oiled the pivots and squeezed a bit of oil in both ends of the cable housing)

    The front chainrings don't look like they are in terrible shape?! The middle one is worst and I think the small one is ok but it still skips.

    I had a problem with the rear hub. The cone is pitted and because I don't think it was tightened properly. There was some play that I adjusted out.

    I thought a for a bit that perhaps frame/wheel flex was causing things to misalign.

    LBS mentioned to replace front chainrings.

    Any help is really appreciated. (I'll buy you a beer if you live in the Chambersburg, PA area)

    Thanks,
    Rob

  2. #2
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    Check the cable housing length. Stock on some of the FSR's is on the short side, usually the middle piece around the shock and when the shock compresses you get ghost shifting.
    Easy fix is run full housing to the RD.

    Hope that helps.
    Bikes=Sanity

  3. #3
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    Sounds like a worn freehub or freewheel..

    Maybe bent RD hanger...

    Maybe worn dropouts.

  4. #4
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    DSFA, the housing is already full from shifter to the RD. But, I was wondering at one stage if maybe the loop at the back wasn't a little too tight. At one stage a year ago or so I noticed that if I pulled the housing a little further it would shifter somewhat better?!! Was going to replace the housing and cable this winter.

    Jeff, I've seen some tutorials that go through precise hanger alignments but just a week or so ago I twisted up a (brand new..) hanger on my other bike and it ran perfectly after I bent it back by hand?! On the problem bike it seems pretty straight.

    Regarding the freehub, it's got some pretty serious pitting on hub cone opposite side of the freehub?!?! Possible issue?

    Then the dropouts, you're just suggesting that the wheel is shifting around in there rather than staying locked in one spot?

  5. #5
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    Quote Originally Posted by boboTheGeek
    Jeff, I've seen some tutorials that go through precise hanger alignments but just a week or so ago I twisted up a (brand new..) hanger on my other bike and it ran perfectly after I bent it back by hand?! On the problem bike it seems pretty straight. I have straightened some by hand as well

    Regarding the freehub, it's got some pretty serious pitting on hub cone opposite side of the freehub?!?! Possible issue? Yes just grab the cassette and see if it wobbles more than say and 1/8

    Then the dropouts, you're just suggesting that the wheel is shifting around in there rather than staying locked in one spot?Yup I got that problem

    Sometimes you RDs look bent and you straighten them by hand and everything is fine...

    Somtimes you think RDs are straight and you just can't get the thing to shift right....

  6. #6
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    It shifts Ok for now.. except under HD (heavy duty not high def) pedaling.

    I'll check that stuff out.

    Thanks for the experience dude!

  7. #7
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    Is it chain skip, or ghost shifting?

    For chain skip, does the crank feel like when you power down on the pedals, that it jumps a few teeth, then catches? or for ghost shifting, does the chain ride up and down on two or more cogs when pedaling?

    If its chain skip, you already eliminated 2 out of 3 of the reasons chains slip. Chain, cassette, chain rings.

    Since you replaced the cassette and the chain, you probably have worn chainrings. I've fixed several bikes with this issue, even after the customer has replaced the chain and cassette.

    If its ghost shifting, it could be bent derailleur hanger, cable to short over the rear pivot area, or contaminated cables/housing.


    I'd put money on that its the chainring.

  8. #8
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    There is a small potential for the ghost shifting because of the cable binding on the housing?!!? But, I'm not too sure of that.

    When it "skips" it's usually pretty drastic because I'm hammering it pretty hard so the chain could might even fall right off everything and my knee smashes into the handle bars (hence why I'd like to figure it out).

    So, I think I'll try a new chainring and cable with housing. If that doesn't work i'll have a hissy and throw my bike out the window.

    I really appreciate the help! This will be a big deal once I get it licked!

  9. #9
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    Quote Originally Posted by jeffscott
    Sounds like a worn freehub or freewheel..

    Maybe bent RD hanger...

    Maybe worn dropouts.
    or, worn out chain and cassette. replaced both of mine and all's back to normal
    nothing in life is real, so if anything goes wrong, blame the dead guy

  10. #10
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    it sounds like your chainring needs replacing, probably just the middle one. I had same problem not so lonng ago, changed the middle ring (which didn't look to bad) and hay presto...good as new.

  11. #11
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    Cabbgage, looks like you are right. Replaced the middle chainring (even though it looks ok) and that fixed it! Ended up getting a granny ring too.

    Thanks everyone.

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