Cranks?

Will someone please explain to me the exact differences between and cottered
crank and a collerless crank. I am going to buy a Uni and I want to know exactly
which to get. How do they look? Thanks aao4247@acs.tamu.edu

Re: Cranks?

“Antonio A. Ortiz” <aao4247@acs.tamu.edu> writes:

>Will someone please explain to me the exact differences between and cottered
>crank and a collerless crank. I am going to buy a Uni and I want to know
>exactly which to get. How do they look? Thanks aao4247@acs.tamu.edu

COTTERED crank - A crankarm that is held to the axle with a COTTER PIN.

COTTERLESS crank - A crankarm that does not require a COTTER PIN.

You can distinguish a COTTERED crank by noting just above the axle is a “pin”
passing thru the crank arm at right angle. One side of the pin looks like a
smooth round metal knub. The other end looks like a bolt, with a nut tightened
down on it. The pin, which is tapered on one edge, is hammered into the crank
and presses firmly against the axle. The axle has a channel in it to grip the
pin. The nut simply maintains this pressure while you ride it. This design is
NOT recommended for unicycles since the “rocking” motion both forward and back
will loosen, damage, and eventually destroy the pin (cheap to replace) and soon
after the axle (expensive to replace), when the channel gets gouged out.

COTTERED cranks do away with the “pin” by using a squared axle with tapered
edges. The crank arm hole is also squared, with tapered edges. This arm is
hammered onto the axle to assure a snug fit. The very end of the axle is
threaded so that a nut can be added to keep the crank in place. You will
recognize the cranks by noting a dust cap covering the crank hole and the nut,
and more obviously, the smooth contour of the crank arm around the axle, with no
“pin” sticking out on either side.

Hope this helps…

David Winston winstond@delphi.com