|To run only the axle there is a complex operation|
Using higher voltage will be like using a lower gear because it allows more wattage without increasing the amperage (higher amperage requires thicker wires), but then you have to increase the gear ratio even more because the motor will be moving faster at that higher voltage.
Pay close attention to the Motor Power Curve (Red Line) and the Black Curve (Load Line). Typically the Motor power curve will rise up in an arc, and then abruptly fall off on a straight line down to "0" The highest point (Apex) of the motor power curve is when the motor is demanding the full current output of the controller (and where it is least efficient).
If the Load line intersects to the right of the apex of the motor power curve, then the controller is powerful enough for the system. If the load line intersect the motor power curve to the left of the apex of the motor power curve, then the controller is too small, and we should look for a more powerful (higher current) controller.
For example, in the plot above, we see that it takes about 3200W (motor power) to push that bike to 45mph. Using the same efficiency as shown (86.9%) we see that although it takes about 2680W (battery power) to achieve 40mph, it would require 3200/.869 = 3680W (battery power) to get to 45mph - a fairly staggering increase for 5mph - but perfectly understandable when you look at the steepness of the Load Line at that speed.
Converting a hub motor to a middrive motor
|do not put a hub motor on the front wheel!|