It's the sizing of each of the compartments. The compartments are both labeled as small, but the stoker's top tube is about 1.5 inches shorter than the captain's. I've ridden in both positions on it. I'm 5'5" (almost) and the stoker's compartment is a little small for me. It seemed fine until I started riding a single! The captain's is a bit of a reach, but not awful. I did Cinderella on it as captain.

If you guys want to try it out, you're more than welcome to next time you come down this way.

V.