Engineering students at Yale University wanted to build a bicycle unlike any other, so what did they do? Go with a single-speed, spokeless design of course. To be more specific, they “used two cranks and two bottom brackets in the front to gear up the ratio; it goes from (IIRC) 53 to a 13, which is connected to the second crank and another 53 which connects to the rear hub.” Click here for first picture in gallery.
The rear hub is just a normal ratcheting rear hub that we mated to our belt pulley. Not sure if all these bike terms are right, but that’s the general idea.