I'll be "rolling my own" ebike over the next few weeks. Planning to use a 400watt counter-clockwise motor to drive a left side crank sprocket. Rather than messing with a hard to find freewheel crank sprocket, it seems like it would be better to put a freewheel sprocket on the motor instead. It would need to freewheel the opposite direction of a right side sprocket. And it would need left had threads so the torque doesn't unscrew it.
Anyone know if a standard freewheel sprocket can be screwed on from it's outside, as in backwards?
If not, are there left side freewheel sprockets out there?
I'm not sure most people realize how much energy just a chain rolling around a couple sprockets can soak up, especially as we pedal along with our 100 watts or so of muscle power...so for that reason, I would sure try to have a left side freewheel sprocket on the wheel, and not the motor, which I hear are quite easy to get.
The deal is, it's fairly cheap to get a hub motor and controller from Goldenmotors or Electric Rider, it's hardly worth the trouble of building it any other way, unless of course, you already have the other stuff, or you want an outrageous top end.
My plan is to have a 400w motor mounted above or in front of the pedal cranks. It will turn counter-clockwise with the shaft pointing to the left. The shaft will have a small sprocket connected by a chain to a large crank sprocket. This way the motor gets to take advantage of the bike's gears, just like the human does.
What I was hoping to do is to allow the motor to run the bike without the pedals moving but the more I think about it that's not going to happen...
xtracycle, electric recumbent, downtube folder and more
Hostel shoppe lists it under cranks and then Sun Bicycle Indepent Pedaling System. You would want the stoker version. I have one if you want photos. It is made for 170 mm road gears but I am pretty sure I will be able to drill it out for 110 mtn bike gearing for a utility bike and the hills around here.
There is a thread on endless sphere about rewiring the motor. If you don't have one yet, Cyclone Taiwan will sell you one that goes CW or CCW.