Bafang are known to be conservative in the specs on their web page. ebike.ca sells two even faster winds for 20" and 16" wheels, see the wheel I posted further up the thread. Maybe their standard wind is done specially for them? They have a testing machine to read out the actual rpm/v IIRC.
In any case with my planned 14S 48v battery hot off the charger even at the bafang 7.6v/rpm that equals 445 rpm and at nominative voltage 393 rpm which is a bit too close for comfort. I will follow Bafangs recommendation and keep the current down, for the planned use I don't need over 500 W anyway just top speed between 45-50 km/h.
This motor is really a positive evolution in hub motors:
- cable comes out of axle side not end (I am about to rewire my mates front bafang, he fell of and cut the cable at the axle end...)
- light weight - 2.5 kg which saves 300 grams over my Mxus. Less than 3 kg in the wheel with the Chinese 11-42 cassette I am trying out
- easy to take appart for maintenance and to add oil cooling
- loads of torque because of high internal rpm