Electric generator->battery->electric motor drive train should be fairly efficient. I'd be surprised if it was lower than 80%.
Traditional dynamos are fairly small parasitic loads and not really comparable.
Traditional dynamos are fairly small parasitic loads and not really comparable.
Lets be charitable and call it 90%, it's still going to charge the battery (which is described as a buffer), and that will have a max of 95%, discharge the battery, same, and power the motor, which has likely the same efficiency. You're at. 9.95.95*.9 = 73% efficiency at motor output. You're giving 27% to the gods of thermodynamics, unless you like the extra complex cardio you're getting, I don't really see the point. Regular bike transmissions are not free either, but they're closer to 95%.
Thinking about all that, I don't get why they didn't use a hub motor. Why adding a belt when you could have transmitted the power directly to the wheel?
Also presumably we should be comparing the efficiency to other ebikes not traditional bikes. I'm not sure how effective traditional ebikes are at integrating motor + human power together but I'd imagine there are some additional losses.
80% is really bad for a bicycle. A well-maintained bicycle drive chain is basically 100% efficient.