How to calculate the output torque of motor in ebike wheel ?

Torque and output power


The Brushless electric motor Calculate formula: Power (KW) = Torque (Nm) X RPM /9549

Speed and torque relationship
So under the condition of constant power, the slower the speed, the greater the torque




How to calculate the wheel output power ?
Caluclate formula:Input torque * transmission ratio = output torque


For example:
FLIPSKY 6354 140 KV controlled by a VESC 4.20 Aluminium Heat sink on a bike with a 36 Volts battery (10S4P). The ratio of the gear is 22:248 The motor torque should be around 5Nm, and I expect minimum 50Nm wheel torque.

Question:

minimum 50Nm wheel torque can be achieved ?

Gear ratio


Calculate according to the above formula:
Input torque * transmission ratio = output torque
5Nm * (248:22)=56.36Nm

So the minumum 50Nm can be achieved.