So I managed to get the right sized cotter pins. Without installing the cranks onto the spindle, I could drop the cotter pin through the hole.

However when I attached the spindle, the pin won't go all the way in. It's only roughly 2/3 of the way in. The nut and washer fits on but The pin head itself isn't flush with the cranks.

Does this matter? I thought it's the taper of cotter pin that prevents the cranks from moving anyway.

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  • 1
    It looks to me like you failed to get the flat side of the pin against the flat spot on the crank axle. Apr 17, 2019 at 16:06
  • If the correct size pin is installed correctly there should several threads exposed past the nyloc nut. (see the non drive side photo) The crank side is either not installed correctly or not pressed in tight enough.
    – mikes
    Apr 17, 2019 at 20:15

1 Answer 1


For a correct installation the top of the pin does not need to be flush with the crank. The last picture in this how-to article is of a correctly installed pin and it is not flush. As long as the flats of the pin make correct contact with the spindle and the pin goes through far enough to have threads sticking through the nut it's OK.

Keep in mind,

You cannot get a cotter tight enough by tightening the nut: you must use a press or a hammer. Cotters are made of fairly soft steel, so that they won't damage the axle. If you try to tighten them just by turning the nut, either you won't get them tight enough, or you will strip the threads.
After a cottered crank has been re-assembled, the bicycle should be ridden for a few dozen miles, then the cotter re-tightened with a press or hammer. If this is not done, the cotter will probably loosen up. If the bicycle is ridden with loose cotters, the motion of the crank will cause the axle to cut notches into the cotters, and it will become impossible to tighten them. https://www.sheldonbrown.com/cotters.html

  • +1, looks like it maybe wasn't pressed in. Also I believe but am not totally certain that if the spindle flat isn't making full contact with the pin, which may be happening here, the taper face of the pin needs to be filed to be longer and shallower. Apr 18, 2019 at 0:26

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