No such thing as zero resistance. Even a standard bottom bracket cartridge has resistance, it is just very low. With assist off I feel no additional resistance riding the tongsheng. If you spin the cranks on a stand there is a definite difference, a good twirl spins many times in either rotational direction with a standard cartridge and chain removed, the TSDZ2 will spin a slightly less when spun in reverse where the sprag clutch is disengaged, spun forward it doesn't spin as well - then it has to overcome stationary inertia of the large main gear (which weighs about a pound and a half in and of itself) as well as friction with the meshing and turning of the gear - less so with the small reduction gear and the one way bearing (disengaged). I don't see why a Bafang would be any different unless the main gear is heavier and/or the bearings are tighter. The motor shouldn't be turning at all pedaling with assist off. The luna video I posted shows how hard it would be if the one way bearing is jammed, then you are trying to turn the motor over at a whatever rpm the reduction ratio dictates.