d8veh said:
I'm talking from experience. ... It's very easy to get a false impression of the power on a short test ride.
d8veh, I don't mean to get into a bun fight, but having owned a number of ebike motors, front hub, rear hub and now crank drive, I am talking from direct experience rather than general experience. Have you actually owned a crank motor that drives a rear hub bike, and if so, what type? Until the BBS01, I had not, and it was an eye opener. Previously, we were finding it very difficult to hit the sweet spot between a right-torque, right-top-end motor. Some could not pass the killer-hill test, others had too much power - no longer bike riding, but "mopeding". The closest to sweet spot we came was the Bafang CST motor... until the BBS01 came out. I'm not as good at engineering as you, and cannot explain why, but in real life performance, I feel they got it right. It does have a few things I would like Bafang to do better (and the company is not set up for retail sales), but overall, its a well-executed motor. We are now putting together a bulk order (ten motors so far) of people on our island who have tried out our bikes and like them... it's a co-op group, not a business, and we still have not verified we can actually get the order processed, but I will keep folks updated on our progress. I did get an email from a person in South Africa who wants to put together a buyer's group, so if this works, I'll let everyone know (BTW, we run a charitable trust... making a living off of ebikes would be in the too hard basket).
On a three-speed rear internal hub motor, in top gear the power assist is strong enough to maintain speed. I am using it regularly now in widely variable terrain and under conditions that include the roaring 40's wind of New Zealand and I continue to be impressed. The one motor now reads 84km on the odometer, the other 23. The first job they must do every day they are used is to take me up a 15 degree hill that serves as the torque test (it was too much for a number of "higher powered" 350W front hub motors we bought). On that hill, I must pedal, and it is better if I am in low or 2nd gear. In second, I have to give it more muscle. I would say the speed with the motor up the hill is about 15-18kph (which is the speed four of us pedalled the Bella Ciao along the Elbe River for five days on flat paved bike roads before we brought those Bella Ciao bikes home and added motors). Without the motor, I can barely make it up the hill in the lowest gear - leg muscle spasm, lungs hurting, and sweating profusely (it is a long hill). Then along a winding road that has some hills and dips where I set the motor boost to zero on the dips, back to three on the hills and occasionally give it the thumb throttle boost if the angle increases. Then down a steep hill to the ferry with no power, and on the other side a city that begins flat and then has urban hill conditions.
At no time do I sense that I am running out of power assist, and while I feel warm, I am never sweating, feeling muscle ache or lung scream. Of course for every rider, the setting of the gears becomes important. The front gear is a single Bafang 46 or 48 tooth chainring. Thus, the rear gears will determine the relative effect of torque. I expect it could be possible to use small rear gears that are too high for the motor, and there may be bike frames that are harder to move (fat MTB tyres for example) but that is not the case on either of the bikes we use.
Yes, if a rider is looking for a moped (no pedalling and up to 50 km/h) then this is not the motor for them. I agree with you there. But I disagree that it lacks sufficient power at higher speeds.