The diameter of the drum is based on the perfect speed range of an 4 to 6-pole induction motor in relation to towing hang- and paragliders.

If you use a Ø125×5,6mm pipe, it will almost fit perfectly to the sprocket carrier.
This pipe is a bit too thick, but can be turned down in a turning lathe.

6 hooks can fasten the sprocket carrier and the pipe together.