A major ranking criterion for electric bikes is the torque rating of the motor. Generally speaking, bikes/motors with higher torques are sold at a higher price than bikes/motors with lower torques.
As a follow-up of this thread, I get that having a bigger torque helps in torque intensive situations, like hill climbing.
However torque can easily be multiplied/demultiplied using gears between the wheel axis and the motor axis. For example, these gears can be dedicated (embedded in the motor itself) or in the transmission system of the bike.
So the torque that matters is the final torque on the wheel axis, not the torque output on the motor axis.
So, this implies two questions:
- Use of dedicated gears to change output torque: Why is torque rating sold as a discriminatory constant of the bike (especially for the price), where it's easy to just add a gear on the motor itself to increase the torque, at the cost of increased RPMs of the motor axis (as it's done on electric cars)?
- Effect of the transmission system on the motor torque: Since motors can be hub motors or mid-drive motors, the motor is not at the same transmission step: meaning the same motor output torque will not have the same impact on the wheel torque.
For example, a hub motor with a torque of 50 Nm will provide a final torque of 50 Nm to the wheel. However, a mid-drive motor with a torque of 50 Nm, with a gear ratio of 0.5, will provide a final torque of 25 Nm to the wheels.
With this in mind, how to interpret the advertised torque for a bike with a mid-drive hub, since it's heavily dependant on the transmission?