Unless I'm mistaken, the efficiency gain is from shortening the length of the pivoting pins to just what's required for connecting the conventional outside chai

Unless I'm mistaken, the efficiency gain is from shortening the length of the pivoting pins to just what's required for connecting the conventional outside chain links to the saddles. In a conventional chain the pins cross the sprocket teeth and must rotate across that entire width; more frictional loss. In this design the saddle seats on the tooth, and just the relatively short pins linking the saddle to the outside chain must pivot.