For the speed controller we recommend the Infineon 9 fet 36-60v 30a. This controller stays very cool and it is easy on the motor.
The Infineon 6 fet 36-60V 25a is also a great controller for all motors, especially high torque windings or in cases where you want to be more efficient and easiest on both motor and the battery.
The Infineon 12 fet 36-60V 40a is useful for more power in higher speed 6T and 8T motors and guarantees cool controller under extended continuous operation. But it is harder on the motor and gears. It is not recommended for the high torque 10T and 12T motors unless you further limit the current. You should use a battery capable of 40A continuous or more such as the ElectroRideTM Ultra High Perfromance batteries capable of 65A continuous 100A peak.
The Infineon 6 fet 36-72V 25A is only for 20" wheel builds or smaller. Running motor @ 72 volts is not recommended otherwise.
All controllers are Cycle Analyst Compatible, and can be used with a 3 power level switch, cruise control, and e-brakes.