Crank bolt broke

HrVad
HrVad Posts: 5
edited May 2014 in MTB workshop & tech
I recently replaced my BB - a Truvativ Powerspline.
Today, after about 55 km of XC riding since the BB replacement, the bolt that fastens the arm to to BB, just broke and the arm fell off.

About 2 km before it happend i checked that everything was securely fastned; no play, everything tight.

The bolt seems to be broken just barely "within" the splined axle.

How could that happen?

Comments

  • supersonic
    supersonic Posts: 82,708
    Doesn't happen often, granted. Maybe a cheap defective bolt? Did it come with the BB?
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  • HrVad
    HrVad Posts: 5
    Don't remember if it came with the BB.
    Could it be if it was fastend with too much/high torque?!
  • The Rookie
    The Rookie Posts: 27,812
    Too much torque or not enough so the arm was moving and loading the bolt, could be either!
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.

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