reohn2 wrote:I know nothing about the Yosepower kit but in their specs linked to by Philig they claim 30Nm torque whilst Bafang mid drive claim 80Nm, Bosch and other big names are all claiming 70Nm+
You have to take the quoted Nm rating with a pinch of salt as the figures are indirect drive that has to transfer it through the drive train, hence more wear and tear on mid drive train.
I think it was Woosh bikes on Pedelecs forum who said that the Bosch torque Nm is only at the motor and that in real terms the 80 is equivalent to a hub motor having 40Nm and the 70 equivalent to a hub motor having 35Nm.
Tony at Woosh who is the tech guy has done some conversion figures and said the reason being so is the hub torque is already in the wheel central position and directly drives the wheel/gearing so doesn't have to convert the torque via the drive gear.
Another forum user on there also stated that with increase torque that Bosch and other mid drive producers claim, isn't purely down to internal gearing and says it is down to the wattage output of the drives which seem to bee increasing from the original 40/50 Nm drives.
For instance Aikema are more up front with their torque figures and for their mid drive state 80Nm/250w, 100Nm/350w & 120Nm/500w drive figures.
The Aikema128sx cassette hub motor they claim >60% Nm for the 500w geared hub, which ties in with that which Woosh quoted.