Alan B said:
Some of the IGH's do work well with mid drives. That would be a good setup. Maybe opt for fewer gears to get a more rugged drive.
Belts are probably not worth the trouble and expense. A spare chain is probably easier to carry, and belts require breaking the frame or strange frame geometry to install, and they require a lot of width as well as uncommon sprockets.
That's a shame. I demo'd a Faraday Porteur that had a belt and I really liked it. Sounds like it's not easy to install on an existing frame like the Xootr Swift, though.
If you want lots of reliability then 2WD might be interesting. Geared hub in the front, and either DD rear hub or mid drive. Not going to be light though.
Lightness is a must, otherwise we're talking a whole different build. If I can't comfortably lug it up the stairs 5x per day, then it's going to be a beastly stealth motorcycle, weight be damned!
Do you ever get flat tires? Mid drives are quick and easy to change tires, hubmotors not so much.
If you want to use a less common mid-drive, buy a second kit for spare parts and go for it!
I run Schwalbe Marathon Plus tires on the Brompton so I never need to worry about flats. I used to run the regular Marathons and flatted about 2x per year so I upgraded. The XB-300 is running el cheapo 26" mountain bike tires which I'm sure do not have any puncture resistance, but the rubber treads provide enough of a buffer that I haven't had a flat so far. On the Xootr I'll probably grab some Marathon+ since I like them on the Brompton.
I'll probably sell the Brompton to finance this build, so I don't have severe budget restrictions, but that doesn't mean I can afford a second motor. I'd rather use something that doesn't need parts shipped across the Pacific, so I'm thinking I have 2 options:
1. Hub motor and medium-sized battery. The double-torque motor weighs 6.5 lbs and a shark battery is another 7.5, figure an extra lb for controller and various housings and mountings and that's 15 lbs. 22 lbs for the pedal-only Xootr Swift is pretty typical so that's 37 lbs total. I could go with the Cute Q100H and save 1.5 lbs and a small amount of money, but I would lose the ability to power up hills on motor-only and support from a US-based company. Still an option, though.
2. BBS02 and small battery. The motor is 10 lbs and the Mighty Mini battery is only 3, so that's 35 lbs. I'd have even more torque in case I needed to tackle some of SF's gnarliest hills (the ones on my route are pretty mild, though) and higher top speed so I could fulfill my goal of briefly merging into traffic when the bike lane is blocked. I've heard that mid-drives feel better than hubs, too. I'd give up the redundant propulsion systems, some excess range (either option would be more than enough for my daily route though), and the ability to relax my legs and let the motor do all the work.
I'm leaning towards option 1, but I could easily be talked into #2 if there are considerations I don't know about.