Now...if that doesn't look like a bunch of scrambled eggs to you, I don't know what will. This, my friends, actually works! It's what we call a "Retro-Direct 2-Speed."
What a Retro-direct drivetrain is....confuses me. What the result is, though, is pretty cool. Basically the bike has two freewheels, each with a different number of teeth. Both are mounted on the same wheel, and both coast in the same direction. The chain engages one, passes through some kind of idler (in our case...we used a ran-sacked derailleur pulley), and coasts over the other, back to the crank.
Why, then, is this so cool? Because when you pedal backwards, you engage the other freewheel.
Pedal Forward: One gear.
Pedal Backward: A completely different gear.
Boom. Just blew your mind.
...I had a lot of fun yesterday pedaling backward down the street. You know what kind of looks you get when you do that?