Hub Motor Selection for BMX project

[Kawgomoo]

Hey all.

My 9 yr old wants to electrify a BMX bike we've got laying about. Im having a bit of trouble selecting the correct motor for our needs.

20" wheel

750W or greater.

110mm rear drop out.

14mm axle with 14mm flats.

Single speed free wheel.

I don't mind machining a custom axle for it if need be....but the easier the better

Any advice is greatly appreciated.

 

[dogman dan]

Very similar to the one I just answered about 150mm into 135.

In this case, if the bike is steel, you can bend out from 110mm to a bit more. But you won't have a coaster brake anymore. If already rim brake, no problem.

Using a single speed freewheel, you might not need to bend the frame at all, or at least not much. Depending on the actual choice of motor, you may have to cut a new axle shoulder on the motor on the gear side. Or you might simply need to shorten a spacer that comes with the motor.

If the threads now stick out too far, add washers and torque arm till the nut can again put pressure on the frame.

The other simple way for bmx,, is forget pedaling. front motors can be run on the rear of a bmx frame, squeezing it in 10 mm.

 

[amberwolf]

https://endless-sphere.com/forums/viewtopic.php?f=30&t=37837