Short discussion on how motor power affects motor speed and torque by using a stock 36V 250W Fiido brushless geared motor and comparing it to a 36V 350W geared motor.
Listen to the sound of the motor. The speed increase is nothing to shout about because we are still using stock controllers after all, but the torque will increase by as much as 40%!
To get a leap in top speed, we will need to bump up the voltage to 48V or more. Assuming the stock controllers, a 250W motor can only hit a top speed of 24kmh, but a 350W motor can hit a top speed of 27kmh. However, if we increase the voltage to 48V, the 250W motor can hit 28kmh but it will burn out very quickly. The 350W motor will be able to hit 32kmh with relative ease.
Of course there are many assumptions and configurations that we did not consider, but this is just to kickoff discussion.