Here's the deal: one of the BB shells is oversized, so it accepts an eccentric enclosure for the BB - this is necessary to tension the timing chain - the chain that connects the two chainrings. However, I can't use this eccentric to tension the chain that goes to the rear wheel, for obvious reasons - I don't want to have the timing chain slack.

Luckily, the rear dropouts are horizontal, which allows for the rear chain tensioning.

Unfortunately, there are two sets of V-brakes on the rear wheel (so both cyclists can control or add to rear-wheel braking), which makes it f@cking hard to adjust the wheel. Last time I changed the rear tire, I spent the best part of half an hour adjusting the 4 brakepads. And in case of a tandem, you need to adjust for a stricter tolerance, as you are going to brake a much heavier vehicle.

Anyhow, yeah, technically a breeze. I just hate those V-brakes. I was thinking of using a rollerbrake in the rear. That requires 0 adjusting, which is nice.

Downside to the rollerbrake: not safe for stopping something that's 250+ lbs. Dunno why, it's probably too weak, or it overheats? But rollerbrakes are so sweet, otherwise.