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crank arm help

GJCGJC Posts: 198
edited January 2013 in MTB workshop & tech
Hi need help just sheared grip (for axle) in left hand crank arm due to retaining plastic bolt fell out felt lateral movement but damage was done. I want order a new crank arm the measurement from pedal to hole is 170mm would i assume this maybe the crank arm length?

Many thanks GJC
Lapierre Spicy 316 2011

Posts

  • cooldadcooldad Posts: 32,599
    Centre to centre.
    What cranks are retained by a plastic bolt?
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

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  • HylolHylol Posts: 11
    That's correct. You measure crank arm length from center mounting hole for spindle to center mounting hole for the pedal.

    If you're in doubt at all, remove the right hand pedal and measure that crank arm.

    Detailed drawing (courtesy of SRM): http://mywheelsandmore.com/Images/bicycleParts/chainset/Bike-Crank-Arm-length-Determination.jpg
  • GJCGJC Posts: 198
    sorry not plastic bolt just plastic retaining screw on shimano slx crank, thanks for the replys just noticed its says the length on the inside of crank arm.

    Many Thanks GJC
    Lapierre Spicy 316 2011
  • nicklousenicklouse Posts: 50,675 Lives Here
    the preload bolt? just order a new one.

    or are you on about the 2 clamping bolts?
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
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  • cooldadcooldad Posts: 32,599
    Once the pinch bolts are tightened the preload bolt won't make any diiference if it loosens.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • cooldadcooldad Posts: 32,599
    But it shouldn't move if the pinch bolts are done up.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • GJCGJC Posts: 198
    Thanks for the replies, the preload bolt wont stay in, it makes its way loose and the teeth inside the crank that slides on to the axle is sheared, when preload bolt tighten and pinch bolts tightened there is lateral movement

    many thanks GJC
    Lapierre Spicy 316 2011
  • nicklousenicklouse Posts: 50,675 Lives Here
    so get a new preload bolt.

    or your bearings are dead.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • The RookieThe Rookie Posts: 27,802
    Have you enough spacers? Withe the preload tightened there should be no lateral movement, either it's bottoming on something and not pulling the NDS arm in, or your bearings are too close together.
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • GJCGJC Posts: 198
    Thanks once again for the replys, the only way to fix it is buy left hand crank arm. sorry for the confusion in the crank arm the groves that slide on the axle, these are sheared. no grooves, just smooth so crank cant grip to turn axle when pedalling.

    Many thanks Glenn
    Lapierre Spicy 316 2011
  • Chunkers1980Chunkers1980 Posts: 8,035
    I'd buy a whole new crankset, it'll workout better value.
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