You can get or make a Hall Effect gear tooth counter to count gear teeth or spokes attached to that hub. Put a button magnet behind a Hall linear sensor (not a Hall switch)) and any close ferrous metal will change the field strength that the sensor detects.
If you can center and glue a steel ring (can metal?) with holes in it to that hub then Hall switch on outside of the ring should detect stationary magnet on the inside whenever a hole comes between. But how small a hole will work at high speed?