https://cyclingindustry.news/bafang-debuts-first-motorized-e-shaft-drive-system-for-public-bikes/
but wouldn`t we need a special frame??
frames for shaft drives are easy. You only have to replace the bottom bracket shell and the drive side chain stay.
Shaft drives for pedal cycles are nothing new, in fact ,most new things are really updated and refined ideas,...but getting back to shaft drives,for unpowered bikes they are inefficient, they might be useful for cargo box trikes and long cargo bikes, the problem is restricted gearing, i.e. you can't gear them high enough without bulky and heavy gearboxes.
The same article mentioned a mini hub motor, 1.4kg - sounds just the right kind of weight for next year bikes.
A decent reliable mini hub would be great. Tongxin to fragile, keyde seem also unreliable and expensive, the mini crank from gng is untested and stupidly priceyHaving owned a few shaft drive motorbikes (that's my Yamaha XJ750 in my avatar). I think shaft drive would go well with electric bikes.
The efficiency loss not such an issue and there nice and clean with low maintenance.
The forthcoming mini hub motor mentioned in the article is even more welcome for me. All the UK kit suppliers seem to supply lardy hub motors of 3 - 4 kg even though excellent lightweight motors like the Q100 have been around for ages.
Hopefully this mini Bafang will be a good un and available in the UK in time.
A limited gear choice was also the Zerocycles problem, in their case only the old Shimano 7 speed hub gear but not the newer 8 speed ones. It's that sort of inflexibility that limits shaft drive adoption. Their designers should offer versions for all the best hub gears, Shimano 8 and 11 speed and the Rohloff 14 speed.The Paris bikes didn't seem to take much power from the shaft drive, I suspect the gearing problem is the big issue, I think they had just three gears.