One other thing that I forgot about the devil's spawn, If the angles on the cotters weren't closely matched and/or the cotter holes in the crank arms were not accurately machined, the cranks might not line up 180° apart.
We had a bike come in for service once that had cranks off at least 20°! I can't remember if it was due to mismatched crank arms or what.
Chas. Colerich Oakland, CA USA
Steve Birmingham wrote:
> Yep, all the stuff the other guys already mentioned. They need to match, and
> sometimes the threads don't
> stick out far enough.
>
> Plus, many of the new cotters are very poorly made. They're just chopped off
> a metal rod, and likely forged to sort of the right shape before threading.
> Often the taper isn't flat, and sometimes it's narrower than I'd like. A few
> even have a bulge at the threaded end of the taper that prevents it going
> into the crank. Careful filing can make it flatter and wider while keeping
> the same angle. A wider face on the taper is better as it spreads the
> pedaling force out a bit more.
>
> Steve Birmingham
> Lowell, Massachusetts
> USA