I'm impressed. That's a new and really good idea for mounting a jack shaft. I've been looking for ways to do that and they have all been WAY complicated. I think the word for yours is elegant. Combining a mount for jack shaft, motor and controller is great.
I picture making the side panels pretty plain. There wouldn't be anything shouting EBIKE. I have an extra Currie (Unite) 1018 24V 450 watt motor, an extra controller and I can borrow my Pings from my other ebike, an eZip. On a reasonable quality mountain bike this should be a good, light, maybe quieter transport. How is the noise level from the two extra chains.
I picture my two extra chains will both be bicycle chains, not one a #25. I don't need as much reduction. The 1018 puts out 550 rpm on a 9T sprocket. A 36T on the left end of the jackshaft and a 20T freewheel on the right feeding a 44T on the chain wheel freewheel should give me about a cadence of 60.
I guess based on your experience I should go for the Sick Bike HD freewheel. It sounds like it is worth the extra $50.
Thanks for the idea. Don
Own a 1988 Rockhopper, Comp soon to be MY1018 powered, a 2008 Blaze recumbent, a 2008 eZip, Trailz Hybrid Electric Bike, with Ping 24V, 15 Ah battery (4,500 miles)and a 1971 Raleigh Super Course bought new, now updated. It's the same bike I love, feels even better.