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  1. #1
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    XT m760 hollowtech "fixing bolt" broke

    my hollowtech fixing bolt broke, and the left crank fell off while i was riding.

    its the black plastic nut with the shimano logo on the left crank, has somebody broke his/hers too???????????? this failure could be catastrophic if i where riding fast! and its making me doubt the reliability of any hollowtech shimano crank.

    any more durable lightweight crankset models???? im leaning over the FSA Kforce carbon cranks, but i havent seen in person how they are "bolted" together...... i dont like any plastics on my crank anymore.

  2. #2
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    That bolt should not be holding the crank arm on, it is just there to preload bearings during assembly. The two pinch bolts hold the crank arm to the spindle and were obviously not tight enough. You should be able to get hold of another bolt and the reassamble the cranks making sure the pinch bolts are tightened to spec.

  3. #3
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    Ditto what Furrner said. You should be able to ride safely with this bolt removed.

    I've seen some instances where the bolt broke due to too few spacers being used, but your example sounds like an undertightened pinch bolt.
    speedub.nate
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  4. #4
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    What you're refering to is the little lockring right? That ring should not fall of if the crank was correctly installed. FYI the crank can NOT be used without that ring. That is what keeps it from sliding off. The only way that lockring could fall off is if it was put on AFTER the pinch bolts were tightened. That is a big no no. That lockring has to be tightened with the bolts loose to preload the crank. When the pinch bolts are tightened they pinch the inner lip of the ring to keep it from unscrewing. There's no way its comming off after that.

  5. #5
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    my crank has been rebuilt many times for a clicking sound my lbs cannot find, perhaps they overtightened the plastic fixing bolt. When it broke, only half a tread was left thus it wasnt able to hold the crank arm anymore from sliding off.

    btw, the FSA crank has an aluminum fixing bolt!

  6. #6
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    Quote Originally Posted by bruno787
    btw, the FSA crank has an aluminum fixing bolt!
    Sure, but if it's K-Force it uses pretty different type of adjustment.

  7. #7
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    Quote Originally Posted by bruno787
    my crank has been rebuilt many times for a clicking sound my lbs cannot find, perhaps they overtightened the plastic fixing bolt. When it broke, only half a tread was left thus it wasnt able to hold the crank arm anymore from sliding off.

    btw, the FSA crank has an aluminum fixing bolt!
    You seem to be missing the point that it is NOT the job of the plastic screw to hold your cranks on, it is there to preload the bearings during assembly, nothing more. The pinch bolts hold the crank to the spindle and were obviuosly not tightened enough to prevent this happening. Rather than spend money on another set of cranks, get a new plastic screw and have the cranks put on by someone who knows what they are doing, get them to tighten the screws to the specified torque and they should work fine. The only problem you may have is if the splines or crank arm have been worn due to your previous problem, if this is the case I would talk to the bike shop about a free/cheap replacement.

  8. #8
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    Quote Originally Posted by bruno787
    my crank has been rebuilt many times for a clicking sound my lbs cannot find . . . t!

    Ralphies Wheelie Shop (Furrner) fixed my clicking noise by retensioning my rear spokes. Several were loose and clicked when put under force from the cranks. Only clicked on the down stroke of the right crank arm but your symptoms could vary.

    And so far you have very sound advice that you should give a shot. I have a set of these cranks and it's not all tat hard to install it correctly if you know what the order is. I do torque the pinch bolts just slightly over spec by about 2-3 ft-lbs.

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