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I want to build an electric motorcycle ( more of an electric bike, actually), but i don't want to use a conversion kit.

I want to take out the pedals and put a motor there (either 12v DC or 220v AC). My problem is how to transfer the power from the engine to the rear wheel: Do I need some sort of gearbox? Let's say I would use a 0.7kw, 3000rpm 220v AC motor: How do I connect the spinning rod of the motor to a chain or belt (it doesn't necessarily have to be chain driven€ enter image description here

Is this a bad idea? Can the motor drive the wheel directly? The whole thing (including the rider) would weigh less than 150kg. 0.7kw is enough for the speed I desire. (I am interested in building a dirt bike actually...)

Excuse my English, I am not a native speaker.

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A transmissions main job is to manage torque. What you have to do is look at the motor spec-sheet and see how much torque it generates. Ensure it is sufficient to get you moving, calculate the friction coefficient with your weight and make sure the torque isn't so high you get wheel spin. Finally tune it to make it comfortable.

But really, this would be more for a "finely tuned machine". Sounds like you want something fun and easy!!! In reality you should just get a motor with a metal rotor(part that spins), weld/bolt it onto the sprocket, and pump some current through it. If your bike already has multiple gears I would say leave them on as you can adjust the torque ratio to accommodate a wider range of electric motors.

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  • $\begingroup$ I have been thinking of using my bike s transmission but i thought it might not be able to take it. $\endgroup$ – Andrei Grigore Apr 7 '17 at 16:43

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