How do I get these spline crank removed?

In the 1960th these spline cranks became common. Reason for this was that they are simply cheaper to produce, but technical inferior - never mind.


Mostly the axle is fixed to the right crank arm. But there are exeptions:


The round axle does have a flat area to fix the crank arm on. The crank arm does have two drillings: one for the axle and one offset and crosswise to accomodate the spline. The spline itself is made out of really soft material and the crank is fixed by creating a wedge to the axle. Usually pedalling forces are transmitted by a small area only. That's the reason this construction does not last long.

To remove the crank arm loosen the nut, securing the spline, until the nut reaches the end of the tread. Turn the nut to be on top of the crank. Now loosen the spline by well hearted hammer blows. Remove the nut and knock out the spline. It's common to destroy the spline while removing, so it has to be replaced. Take care there have been several diameters in use.

After removing the crank the bottom bracket, usually a pressed in Thompson, can be disassembled from the left side.

Pictures with permission by user simsen23.