I took a look at mcmastercarr and searched for the sprockets. Cool stuff. I now see how they work. The tighter the fastening bolts the tighter the hub gets. It chokes the axle. No splines though. Which causes me one concern... Once the hub free-spins (not tight enough) the machine won't go anywhere. It would be nice if it was keyed into one spline.
I like how the sprokets can be changed out seperately from the hub.