At 04:57 PM 2/11/2007, John Betmanis wrote:
>I see in those pictures that the heads of the cotters lead when the cranks
>rotate forward. On most bikes with cottered cranks I've seen (from a quick
>survey around the house), the nutted end of the cotter leads. Is there a
>right and wrong way to install cotter pins and why? Why would this
>Paramount be opposite to what I've seen?
John, Mechanically there is no difference. The end near the threads has a broader face. If the cotters aren't installed firmly enough, they will be loaded in shear, and the broader face will resist shear better. However, the cotters would only by loaded in shear when the power is being applied to the left pedal. So, unless you want to install your cranks 8 degrees out of phase, only one will be loaded across the broad face, whichever way you do it.
I always do it the other way because there may be slightly less chance of snagging a trouser leg on the head than the nut. (Or at least the head end is usually cleaner.) Not an issue on a track bike.
And, it looks nicer in the classic pose for photographing bikes, with the right arm at 3 oclock.
Mark "Real bikes have cotters" Stonich
Minneapolis Minnesota
http://bikesmithdesign.com
http://mnhpva.org