I've been rebuilding a bike that came with a somewhat unusual BMX style 3-piece crankset. The drive side crank is a bolt-drive style, however there is no bolt – just a knob that drives the chainring.
It’s a crmo crankset from a dirt jumper from around 10 years ago. Anyone know what this type of crank is called?
The welds and finish look all factory, so it's likely this is the original design.
To get the crank drive working properly, I needed to make an expander to space out the gap between the crank knob and the chainring (which is very worn). Vid here: https://youtu.be/7d8x7qB7mCk
The spacer is hard plastic and probably won’t last, so I'm keen to find a better long term solution.
by jopas_