Torque and high rpms

[JerzyDevil]

Are ebikes better ridden at high rpms to reduce torque and keep the motor cooler?

 

[amberwolf]

It's not a simple answer, because it depends on the specific motor, the voltage you run it at, the controller it's being used with, the terrain / etc you're riding on, and so on.

To see how the relationships all work together, you may wish to experiment with the motor and trip simulators over at ebikes.ca; the instructions on how to use them are below the simulators themselves.

 

[neptronix]

Motors are designed to operate at certain RPMs, and exceeding those, you can either lose, or gain power depending on how the motor was designed, and also, how much additional load you are putting on the motor.

Staying within, or below the rated wattage for a motor is a good way to keep any motor running cool.

I agree that the ebikes.ca simulator is a great tool to help you understand motors in motion / over time / in various load conditions.

 

[Chalo]

Are ebikes better ridden at high rpms to reduce torque and keep the motor cooler?

Most of the time (and I'm talking about brushless 3-wire motors here), the motor makes maximum efficiency at about 80% of its free speed. It will make maximum power at about 50% of its free speed, but at a lower efficiency with much more waste heat. And at any speed below 50%, the fraction of energy lost to heat increases.

Note that "free speed" in this case is whatever top speed the free running wheel reaches at whatever throttle setting is used. So there's not much efficiency penalty for running slow at low throttle, only for running slow at full power (like up a steep hill). There is a small efficiency hit across the board when using partial throttle, unrelated to running speed.

I like to have abundant power and a fairly low free speed, so my bike will accelerate competently up to an efficient cruising speed at full throttle.