Hub motors dont put out much torque, OK if its Flat & going faster is the goal.

My Local Shop has mid drive conversions, screws in where the BB goes.

MTB Elk hunters and fat bikes as beach buggys are the users. (around here)

Bosch type mid drives need be part of a new Bike since the frame is made around the drive.


Raleigh sells a $3K bike like that

Efficiency testing parameters are something you may be able to do,

in Engineering Labs at the University level ..