[electro wrks]

You might find the swing arm is too flexible, twisting wise. The large diameter, short piece of round tubing near the forward middle of the swing arm may be an undesirable flex point. Replace it with a triangulating tube of similar cross-section of the rest of the swing arm tubes and increase the size of the shock mount cross tube to increase the overall torsional stiffness. This is of course only necessary if the swing arm is too flexible.

Asymmetrical forces from the pull of the drive chain may also twist the swing arm excessively in its current design.

 

[electro wrks]

Exposed outrunner motor + no fender + mud = problem?

 

[electro wrks]

I don't know Rip. May be a weak upper shock mount pushing into the batteries? Too much anti-squat built-in with the downward angle of the swing arm?

 

[electro wrks]

So, if the SA were angled up so that the rear axle was above the level of the pivot point, could tire thrust be used to counteract the jacking effect? Although, this would be bad for ground clearance as the bike is currently configured.

 

[electro wrks]

Turn the motor 90deg and make it shaft drive !......."simples"

And, a whole different set of torque problems? Has anyone encountered serious problems with electric shaft drive set-ups? Or, is it manageable?

 

[electro wrks]

I'm thinking with an electric motor, with the max torque of the motor available almost instantly, the counter-torque reaction through the frame or swing arm can also be almost instantaneous. This is the reaction the rider has to compensate for to keep the bike from tipping over in the case of a shaft drive or pogo sticking in the case of a swing arm mounted motor. With a ICE, the rider has more time (say a second or 2 or more) to compensate as the clutch is slipped and the RPMs and torque build up.