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chain skip

mrleemrlee Posts: 499
edited July 2012 in MTB workshop & tech
got a slight problem. rode the bike to work yesterday and the chain kept skipping. so in my lunch break (of course) i set about trying to fix the problem. i pulled the cables through and indexed all the gears and everything was working fine. i replaced the chain, cassette and chainrings last week, and the freehub is fine. so i was riding home and every thing was working fine for the first 2 miles until i "bunny hopped" off a curb. the chain started to skip again :x

when i built the bike up i didnt have a front mech to fit, so i made a homemade shim to get the mech to fit for the time being. am i right in thinking that when i bunny hopped that curb, the front mech may have slipped out of position causing my chain to skip? or am i barking up the wrong tree?

Posts

  • Chunkers1980Chunkers1980 Posts: 8,035
    Wrong tree. What's your gear setup? Parts ect...
  • nicklousenicklouse Posts: 81,520 Lives Here
    And in what gear or is it in all?

    Also what bike?
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • mrleemrlee Posts: 499
    cotic soul

    shimano deore front mech (think its off a 21 speed bike though), xt rear mech (9 speed), deore shifters.
    sram cassette (9 speed), sram chain (9 speed) and superstar components chainrings.

    seems to be happening when on middle and outer ring on the front. rear seems fine
  • nicklousenicklouse Posts: 81,520 Lives Here
    so the chai is jumping off the chain rings?
    what cranks? spacers etc.......
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • mrleemrlee Posts: 499
    seems like

    deore cranks and shimano ht2 bottom bracket. 1 spacer on non drive side
  • According to Shimano:
    If the frame has a 68mm BB shell, you need 2 spacers on the drive side and one on the non drive side.
    If it's 73mm you need only one on the drive side.

    I'd put the spacer on the other side and see if that fixes the problem
    Delete my censored account.
  • mrleemrlee Posts: 499
    According to Shimano:
    If the frame has a 68mm BB shell, you need 2 spacers on the drive side and one on the non drive side.
    If it's 73mm you need only one on the drive side.

    I'd put the spacer on the other side and see if that fixes the problem


    cheers. i'll give that a try. i might get a front mech with the right clamp size aswell (i want to upgrade anyway)
  • nicklousenicklouse Posts: 81,520 Lives Here
    Well you need the correct number of spacers to hold the cranks in the correct place if the can move side to side it will not help anything.

    Measure BB and fit the cracks correctly.

    Don't try anything do it right.

    Your mech will not be the cause as it is not touching anything untill you need to change gear. If it is touching anything it will the the cranks moving if they ave not been installed correctly.


    So before spending any more money check what you have has been fitted correctly.

    If you need to check read Parktools or the makers manuals.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • paul.skibumpaul.skibum Posts: 4,068
    It could also be that the non drive crank arm isn't installed properly and has moved slightly leading to play int eh cranks (rather than the bottom bracket).

    Teh Hollowtech 2 type cranks need the plastic plug in the hollow non rdive end tightening up then the two pinch bolts torque-ing up (or as I do it tightening by hand until I think they are OK).

    If the end plug isnt there and the bolts aren't tight the crank arm can shift off the end a bit and leave play int he whole crank set and cause the chain to shift about.
    Closet jockey wheel pimp censored .
  • cooldadcooldad Posts: 32,601
    Or more likely the spacer is on the wrong side, as above a few posts.
    I don't do smileys.

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  • mrleemrlee Posts: 499
    ok. so ive put the spacer on the drive side now. everything seems to be running smooth on the workstand. will ride it to work tomorrow and see if its solved the problem.

    cheers guys :)
  • nicklousenicklouse Posts: 81,520 Lives Here
    So what cranks? What BB width? How many spacers where?
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • mrleemrlee Posts: 499
    nicklouse wrote:
    So what cranks? What BB width? How many spacers where?

    shimano deore cranks, 73mm BB shell, 1 spacer on drive side
  • cooldadcooldad Posts: 32,601
    mrlee wrote:
    nicklouse wrote:
    So what cranks? What BB width? How many spacers where?

    shimano deore cranks, 73mm BB shell, 1 spacer on drive side NOW
    FTFY
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • mrleemrlee Posts: 499
    cooldad wrote:
    mrlee wrote:
    nicklouse wrote:
    So what cranks? What BB width? How many spacers where?

    shimano deore cranks, 73mm BB shell, 1 spacer on drive side NOW
    FTFY

    :)
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