Is there any regime where this is more efficient than spokes? I'd imagine that at high speed there's an aerodynamic advantage (possibly similar to a track/TT disk wheel?), but I can't imagine the bearings being better than current bikes. But bearing loss might (???) just scale linear with speed, so probably a win from aero in the end. But this isn't counting weight, which I imagine is worse (but doesn't matter much at high speed on flat ground).