OT - electric bikes, hub v rear motor.

[PeterC]

Possibly useful re. the recent thread:

[David]

Yes, that's a pretty good balanced article. Thanks for the link.

If I had to find one criticism, it would be that it's subtly biased to the North American market. For example, it mentions 750W motors. In Europe (and the UK) a motor above 250W would in law make your bike a motorbike, requiring number plates, indicators, tax, insurance, etc.

Also, don't be tempted to buy a direct-drive hub motor, of which there are many cheap versions available on eBay / Amazon, etc. They tend to be efficient only at high speeds (above those allowed in EU/UK law unless your wheels are tiny), and at low speeds they take a relatively huge amount of battery current to produce enough torque, creating lots of unwanted heat in doing so. This means that you need a relatively expensive battery rated for high current delivery. For UK legal speeds, choose a geared hub motor instead of a direct-drive one.

Geared hub motors also have the advantage of a one-way internal clutch, which means that with the motor turned off (or battery flat!) there is no drag from the motor when you pedal. The same isn't true for direct-drive hub motors. (This is also the reason why regenerative battery-charging braking can be achieved only with direct-drive hub motors, not by geared hub motors).

[PeterC]

Possibly useful re. the recent thread: