Newly installed cranks, move up the axle during the first couple of rides. This results in the bolt loosening. Just tighten it up again, eventually the cranks will stop moving. I would'nt recomend you keep over tightening though, as you will likely mis-shape the inside surface of the crank arms.
Newly installed cranks, move up the axle during the first couple of rides. This results in the bolt loosening. Just tighten it up again, eventually the cranks will stop moving. I would'nt recomend you keep over tightening though, as you will likely mis-shape the inside surface of the crank arms.