dirty_d wrote:DC brushless direct drive hubmotors are efficient and can be overpowered without burning up because of their mass, but they are only efficient at a narrow rpm range the same as all permanent magnet motors. so why not use gears with them? mount it in some way where the axle is fixed and the sprocket is replaced with a fixed sprocket, you run the chain from one of the gears on the motor to the rear wheel with a derailleur. you can install one of those freewheel cranks for tandem bikes and run a chain from the crank to another sprocket on the motor. the hubmotors are already designed to run at a very low rpm without any gearing so the mechanical losses in the chain will probably be the same as in a regular bicycle and also be very quiet. id like to do this to my bike but im not really ready to spend $200 on a hub motor.
Stokemonkey does something very similar. But it still costs as much or more than DIY w/ a hubmotor.
It's probably not accurate to say that hubmotors can be overvolted or overpowered because of their mass. All that mass takes longer to heat up, but it would hold that heat too, were it not for its large surface area.
Point being: they are just larger motors, and very possibly under-rated.
Gears can be helpful, but you dont need very many with a motor>500W. Humans have a comparatvely narrow power-band compared to motors, so more gears are helpful there. Motors can benefit from gears for those extreme areas like up steep hills and low-drag/high-speed runs. "Stirring the gears" is not going to help an ebike much, unless it has a weenie-motor.