Removing sheared crank pinch bolt

lorenaustinus
lorenaustinus Posts: 1
in Workshop
I move my left crank power meter across bikes. I try to change the pinch bolts over every now and then, but obviously not often enough as I've sheared one of the 6mm Allen key head bolts, so I can't remove it. It's in a recess into the end of the crank, so I can't grip it with a mole grip or similar. Any advice about how I can get it out myself? Thanks

Comments

  • david37
    david37 Posts: 1,313
    they're a pain in the a to get to, from experience I tried imperial hex sizes, torx, shock release and praying to obscure egyptian gods but nothing worked.

    It's not even a simple job to carefully drill out the stuck crank, not least because its on a freely rotating shaft.

    In the end I carefully cut the crank topside with a circular cutting tool on a dremel until i had cut a slot in the head of the bolt and then turned with a driver. It sounds extreme but it wasn't too bad cosmetically and is not affecting the crank structurally.

    These bolts are susceptible to corrosion and I now ensure that i use antisieze and only tighten to 12nm not the 14nm max and I havent had any issues since.

    The bolts are soft though plus add in a bit of crud and they come out of shape easily. If youre changing them over on bikes regularly they shouldnt have time to seize but its a recipie for rounding out the heads.

    Sooo cut, replace and antisieze a new one, ensure ALL crud is cleaned out of the head and only tighten to 12nm.

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