The recent discussion of crank cotters reminded me of a long-simmering Q. What is the point of filing cotters? If you're using a new matching pair, the chamfer angles are the same, so the cranks will wind up opposite one another.
Is it that the chamfered surface needs to be rougher (smoother?) to have the needed friction against the slot in the spindle? Is it that the cotter may not go far enough through the crankarm without making the chamfer deeper?
Or what?
David Bean
Arlington, MA
beandk at are-see-enn dot com