Originally Posted by
Duragrouch
I know I won't solve this, but perhaps a useful observation:
The chainring on the front crank is tiny compared to the one the same chain engages on the back crank; That means, for both riders to have the same pedal cadence (not necessarily same phase, just same RPM), the front crank is not connected directly to its chainring, the front crank revs go into the gearbox and some sort of overdrive, to output a much faster cadence/RPM at the front chainring, so that front and back are pedaling at the same cadence.
it has a 2.5 gear so for every crack turn you get 2.5 turns on the chain ring so the 18t chain ring is about 46t. so the system is normal in that way bosch does not use that method anymore but it does not feel any different then a regular chainring. its noise though. I have another bike with that and I cant tell the difference between that and the new regular chainring on my other bosch powered bike.