d8veh wrote "Theoretically, the pedal could unscrew itself," I think he meant the crank could unscrew itself ... cause obviously the lh pedal has a left hand screw . Then I think it makes sense . ---- no thats not right! ...Is this business about pedal threads correct?
Unless I am mistaken, with the current set up, any seizure in the pedal would cause it to undo, not tighten up?
Just to clarify flecc! .... Do I keep the crank arm and pedal or do I change the lot?Yes, just use a chainwheel, or spider for mounting chainrings, then fit directly on. Most use square taper mounting, identical on both sides, I'm certain that's one.
P.S. I'd recommend a spider for this application, since it will give the most flexibility for changing the ratios by using different size chainrings as well as different size motor sprockets.
They come with 3, 4 or 5 arms on which the rings mount, and for this I'd recommend a 5 type for the greatest stability under power.
This website will give you the dimensional information you need to get the right spider and rings, Click "Cycle Information" in the side bar, then under general information click "Cranks and Chainsets".
Thanks - perrrrrfectly clear now ...The type of spider you need consists of a new crank arm integral with the centre part and arms, so you onkly need to swap over the pedal. As d8veh warned, make sure the central square taper hole orientation is correct to leave the crank opposite at 180 degrees to the existing right hand one. Here's a pic of one, in this case with a belt ring bolted to the spider. Yours will be a chain ring of course:
Crank with a free wheel would be great for me. With a freewheel I would have to button press for assistance. The freewheel means that my pedal sensor can be used .. which would be nice.. However, I'm driving the crank from the lhs.. which is a shame.. dont suppose anyone has built a "normal" freewheel crank? ...It allows the chain-wheels to free-wheel independently from the pedals. I believe that both chain-wheels together with one connected to the motor.It requires taking the drive off the right side of the motor
Great stuff. Thanks.To make one, you need access to a centre lathe. You pull the chain-wheel off the crank arm, which leaves a spline. Turn the spline to a plain boss of the correct diameter and then cut the thread for a free-wheel. Then you screw on a free-wheel. Weld a bigger chain-wheel to the teeth if you want more than 22 teeth ...