Can someone help me calculating...?

I planned to do a friction drive for a Bicycle or a belt drive (if u have any ideas…).

But I stuck on the planning.
I want the outrunner running directly on the bicycle wheel.
And I want to calculate the max. Speed. Or the ratio. And so on.

Motor is the SK3 6374 149kv on 10s (36-42v)
And a 26" bicycle. And a VESC

Like in the picture…


And also I want to calculate the speed for this option…

For example:
-14T/30T and 26" wheel

Would be very happy :slight_smile:


If my engineering isn’t bad, then I think you can take omega=velocity times radius for the motor and then omega=v*r for the wheel and solve for v?

For the chain you need to incorporate the gearing reduction. Which there is another formula for.

velocity = omega * radius.

1 Like

Idk maybe this can help. But it’s long ago since I used it.

1 Like

Just use this calculator

you should check out
the ebike section is pretty huge. and there are few friction drives already proven. commuter booster