how to know proper DC-motor power(watt) for a bike?

Question

electric bike
what the proper power for motor?
it has chain transmiting

Answer 1

Here is a website that will help you calculate the power needs, depending on weight, desired speed, worst hill, etc.

http://www.geocities.com/mdetting/sports/cycling.html

Generally for decent performance you will need at least 350 watts unless you are small and the roads are very flat. In most states you are limited to 750w (and 20mph) to be under the electric bike law.

If you are using a hub motor, then you will need more power than if you are using the variable ratio chain drive that is connected thru your pedals.

I have a 360 watt chain drive motor, it does just fine. my old 350w hub motor was a little weak on big hills (6% grade, 6mph, total load 350lbs).

You will of course have to pedal your share.