This is pretty simple.
There are two 3/26th holes in the rim. One for a magnet
that activates the Hall Effect sensors and the other
for a brass balance weight. Both epoxied in.

The bolt pattern is yet to be determined as it is not
symmetrical. I just don't have a 10 mm socket
here :)

This goes on the front of the e-shaft on top
of any pulleys.

Paul Lamar

Rather than a brass balance weight, you could use one or two holes drilled in
the circumference the same as crankshafts are balanced; Drilled on either side
of the magnet position. Loctite would also hold the magnet in. Centrifugal
force is not a factor. My $0.02 worth.

Dale Davies