Bafang were showing two versions of their new crank-drives at the Shanghai show last week. The 250w version is available on Aliexpress as a kit now. I think the "750w" one was more to gauge customer opinion, but I'm sure it'll be available soon. I tried both versions in the area outside the halls, which is totally flat, but I was able to gain some useful info.
Both versions are smooth and quiet. No gearbox noise - just the normal motor noise. The 250w version felt a bit less powerful than a 250w hub-motor, but that might be just an illusion because you get a different feel between the high and low gears.
The 750w version had about the same power as my 350w 36v GeNG Gen 2 with 22 amps, although it was much smoother and quieter. It had a 48v bottle battery, so it was probably running with 15 amps. The two versions looked the same, but they told me that the 750w one was a little wider and had thicker wire.
These motors have programmable parameters in the controller, where you can set
http://www.aliexpress.com/item/8fun-mid ... 97760.html
There were also two other crank-drive motors at the show. One was from Ananda, which was a bit noisier, and another similar one - I forget the name. Both of these required a much larger (ca. 100mm) bottom bracket tube, so OEM only.
It seems to me that the Chinese are not very clever in their development. All the motors had crank-speed sensors on them to detect pedalling. Basically, they had applied their hub-motor technology to a crank motor, but then you get a problem with the motor running on after you stop pedalling, which messes up gear-changing. I reckon some customers had told them that European ones have torque sensors, so one or two had torque sensor versions, but they didn't change the controller software. It feels like they use the torque sensor to switch the power on rather than give a proportional amount. You still get the motor running on. They have to go some way before being able to compete with Bosch, Kalkhoff and Panasonic, but I'm sure that they're working on it.
edit by moderator, due to the length of the thread
These motors have many programmable parameters in the controllers' software so that you can adjust them to your way of riding. Theres a thread on how to program them here:
"Programming the Bafang Middrive BBS01+BBS02" (crossbreak, 36 pages)
https://endless-sphere.com/forums/viewto ... 28&t=58780
"Bafang BBSxx - fault finding and fixes" (Slowrider, 21 pages)
https://endless-sphere.com/forums/viewto ... 28&t=58898
"Bafang BBS01 & BBS02 Owners - POST REPAIR CLAIMS!" (teslanv, one page)
https://endless-sphere.com/forums/viewto ... 28&t=61108
In July of 2014
, the Bafang factory began using 9 FETs instead of six
, in the 750W unit that has proven to be popular in North America (in order to spread out the heat, so each FET would run cooler, due to occasional heat-related failures).
In July of 2015
, the Bafang factory upgraded the FETs to the cooler-running and more efficient 3077 FET
(at the urging of em3ev.com). The identifying suffix number on the more desirable 3077 controllers is 206.1, rather than 206