Hi Don,
The residual drag that you have experienced is the result of the magnets passing between each of the separate coil sections of the laminated steel core of the stator.
As the Magic Pie is a direct drive motor, the drag caused by the electrodynamic effect is almost unavoidable.
Although, I seem to recall that some external controllers are designed to supply a low current variable voltage to the motor
(dependent upon motor rpm) which effectively compensates for the residual motor drag and enables the motor to turn freely when pedalling without using the throttle, making it easier to pedal. Unfortunately, GM controllers don't have this function.
Although the large diameter of the Magic Pie motor produces significantly more torque under power, the larger diameter
(and greater number of magnets) also means that the residual drag is more noticeable compared to other smaller diameter direct drive motors.
Most geared hubmotors have an internal freewheel
(unidirectional trapped roller clutch) that allows the wheel to freely rotate in the forward direction while the magnets remain stationary along with the stator.
Although the freewheel mechanism greatly reduces the motor drag, it also prevents the motor from being used for regenerative or electrodynamic braking as the wheel is unable to spin the motor in the forward direction.
Alan
