Originally Posted by
nfmisso
power = torque x rpm.
Power (kW) = Torque (N.m) x Speed (RPM) / 9.5488
Power (HP) = Torque (lb.in) x Speed (RPM) / 63,025
Power (HP) = Torque (lb.ft) x Speed (RPM) / 5252
Torque (translated to force at the road contact area) determines how steep a hill can be climbed, Power determines how fast you can climb the hill.
Was looking into this issue some more
What you write is not entirely true. Given the right gearing between motor and wheel (think Bosh) an inherently low torque motor will perform just as well on a steep hill as a high torque motor, if they put out the same power. At the same power the low torque motor just spins faster and needs a smaller drive sprocket.
Now why then do they advertise torque rather than power? - Beats me. In Europe motors are limited to nominal 250W and that is what is advertised along with the torque spec. However, as I suspected the high torque motors are in reality higher peak power, in accordance to relevant theory. ("torque=power/rpm"). For instance the Bosch Performance CX, 20 mph is 600W max compared to 295W max in the Active line, 20 mph, even if they both are 250W nominal.
https://www.bosch-ebike.com/us/products/drive-units/