Update
Well last Saturday’s first trial run was an unmitigated disaster, thanks to the crappy host bike and its incompetent mechanic (that would be me.) Steerer quill stem came loose while riding down the hill from my house; by the time I’d gathered the right tools and and tightened it back up the sun had set. Then ended up having to walk the bike most of the way back home in the dark because the front rotor had started scraping against the inside of the fork — which it hadn’t done on the stand, was my weight that put it over the edge
So added a spacer in the disc side, which kept the rotor from scraping but caused the six motor bolts on the power side to contact the fork, D’oh! Luckily had spare U-shaped lawyer lip inserts left over from the Grin Tech TorqArms that I hadn’t had to use (since Bafang supplied more specifically tailored hardware in their kit); stuck one in as a spacer there so that the motor cable could exit the axle without getting pinched. Also faced the axles’ exterior steel washers with rubber units both front and rear, makes it easier to torque the end nuts tightly without stripping the threads.
Remaining fly in the ointment, host bike’s drive train components still not all compatible, will have to measure the chain line and figure out how long a spindle will be needed for a square taper BB to replace the current splined unit in order to swap out the FSA Vero 50/39/30 crankset for something a little more mountainy. Because only clamp-on bottom pull FD I could find that works with the SRAM Rocket triggers was an SLX which doesn’t really handle outer chainrings over 44T. Temporarily jerry-rigged it to shift the Vero, but it’s not even close to perfect, can hear the chain grating inside the cage when pedaling no matter how I adjust the cable and everything, grr.
Long story longer, finally got out for a revised test ride late this afternoon and aside from the minor drive train issue, bike handled superbly. Dual throttles no problem at all, easily assists pedaling in any gear with both hubs only on level 1. Have set nominal cut-off speed to 12m/20kph and reaches 11.8mph in actuality. Quieter than the drive train. Of course, do notice the additional weight (~50 pounds more, whole setup probably around 100) but is more stable in a wind and coasts down hill even faster than before. Momentum it builds creates the illusion the bike is still being powered after the throttles are released.
Had been sorta skeptical myself prior to installation regarding whether dual drive would offer more of a benefit than a hindrance, and am pleased to report my doubts were unfounded. The two motors combine harmoniously, don’t feel them fighting each other no matter how I vary the twin throttles. And dual drive really helps to make it over slippery/loose surfaces. Rounding the beach tree middle of my back yard or scaling the hill up to the kitchen landing, powering a single hub either front or rear and the wheel would occasionally spin out; with both engaged the bike just zipped along. Best of all, was finally able to conquer my property’s steep gravel driveway, which curves away from the highway at a perilous angle. Worth the extra price and effort for that convenience alone.
Just managed to squeeze in one lap before it began raining, and upon reaching my back porch the rear wheel began to rub somewhere on the frame similarly to the previous issue with the front fork. Too dark to see where the problem is, but did notice it being off center. Had installed an extra spacer over the cassette so that the chain would have no chance of grazing the stays when on the outer cog; guess it needs to be balanced with a similar or possibly thicker washer inside the disc side. Could also be the misaligned dropouts that I had to saw and grind away to get the squared axle to drop in, resulting in significant lateral play before the nuts are tightened, even with the TorqArm_V4 in place. Anyway, am sure to figure out some kind of fix (even if it means purchasing a whole new frame.)
Happy Thanksgiving everybody!