I finally have a rear disc brake that doesn't rub. The rotor placement on the Leafbike motor pushed the rotor toward the dropout an extra 4mm or so vs the stock wheel, so the stock caliper rubbed no matter how I adjusted the pads.
An Avid BB7 didn't want to fit at all. To make it fit, I had to order an ISO adapter for 160mm rotors, then file areas of the adapter down so that it would be able to mount the caliper to the frame without the caliper rubbing the motor case ad the pads refusing to clear the rotor. It took 4 hours of work hand filing it just right, but everything now fits and the brake works well.
You can even see where a bolt on the stock caliper rubbed the motor case on a previous ride, and I had to cut the end of it off with a hacksaw. It originally had less than half a mm in clearance when installed, and heat or cold must have moved the caliper into just the right position to cause a bolt rub the motor case. I initially thought it was the axle coming loose, but that was not the case upon inspection.
Now I don't have to deal with any of that nonsense. The bike is noticeably more efficient too.
I will soon be upgrading the crankset to a triple with shorter 165mm arms and 28/38/52T gears.
In the future, there may be a 13S3P pack of Molicel P50B for it if I can make it fit in the frame triangle, as well as an ASI BAC4000 running ~10 kW peak and 250A phase current. My goal will be to fit this setup, while keeping the bike as a sort of stealth build, looking as much like an innocuous unmotorized bike as possible, with a 40-ish mph top speed but the ability to out-accelerate many cars to 30 mph.
I plan to install disc covers with vents on the rear wheel to cover the motor and hubsink that will go on it(the vents to allow hot air to escape) while providing a significant aero benefit, hide all wiring in the frame, and maybe go to mountainbike style handlebars up front that have side handles to grip for climbing, cover the triangle area to make it appear as if the hidden battery is actually part of the frame, add a front faring, and make it look sort of like a competition downhill bike.
I think camouflage would be a good paint scheme for that. Redneck it out. Or all-black, and give it a tactical assault urban commuter look to it.
In either case, 10 kW going to a 4T Leafbike 1500W motor will make it delightfully dangerous to operate, but not so much that it can go much beyond the safe limits of the brakes and frame it has. 30 mph is about as fast as I want to go on this, although a 72V pack could allow 55 mph, and I am considering a 20S2P setup as an alternative.
