Isn't this gorgeous?

[Blueberry]

I'm trying to figure out the drivetrain on that. It looks like a singlespeed, but it looks like there is a 2nd ring for the stoker.

Though, for all I know, that may be how tandems are set up.

That's how tandems are set up. The "gears" are on the stoker's pedals and on the rear wheel. Then, there's a ring (usually on the other side) with a chain that keeps the stoker and captain's pedals in sync. Of course, there are some that allow independent coasting, etc. But I haven't seen one

CA