I’ve got a friend who complains her crank is frequently falling off her
Pashley. Is this a problem any other people have encountered? As far as I
understand it, it is well attached, and tightened, but after riding a bit,
the crank gives up and detaches.
jl
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Jeff-
Maybe the internal taper on the crank has been expanded from repeated loosening from the axle. Once it works its way loose, the soft aluminum of a standard crank can easily deform and reduce the surface area in contact between the two parts. The same kind of thing happens with the crank threads when pedals repeatedly work their way loose.
Cleaning both surfaces and using Locktite may or may not solve the problem depending on how big and round the crank taper has become. Installing new cranks will probably solve the problem and doing it correctly the first time (clean, Locktite, TIGHTEN) would certainly help.
At the first hint of pedal or crank looseness from any cycle you have not assembled yourself, all four of these joints should be at least inspected and tightened and preferably disassembled, cleaned, and reassembled using Locktite.
One thing that feels like pedal/crank looseness is the bearing races floating around inside the housings of cheap, plastic pedals. It takes alot of force to make them shift, usually more than you can apply by hand, so the rocking around of the pedal when under the force exerted by your leg can be somewhat deceptive and hard to diagnose.