Don Walker Track Tandem Custom Build 

That was nice tandem bike

I noticed two things, which I would try to do differently. First, the bottom brackets you're using are the sealed cartridge kind. Well it turns out, that the 9-spd Dura Ace road bottom brackets, the ones with the roller bearings inside, which can be serviced, have the exact same dimensions and interfaces as do the cartridge bb's that you're installing. I find the roller bearing bb's to be more efficient, esp. under load, e.g. the stoker bottom bracket AT LEAST could really use that particular bottom bracket. The second thing you may consider is somehow placing both chains on the same side of the bike. This may not be allowed for safety reasons on velodromes, because you have to be really careful that the chains don't touch; if they do, the results could be absolutely catastrophic, and may cause an accident esp. on a fixed gear bike. If you do that, if you place both chains on the same side of the bike (which is more efficient for transferring power from the captain's cranks), you can try to make both chain rings on the stoker's crank more or less having the same tooth count, same size that is. This way, the chains have zero chance of interfering with each other, they will never touch, so long as the lateral distance between chain rings on the stoker's crank is sufficient, with a couple of mm's to spare, for the chains to not touch.

Cool bike

Great photography! # I'd Tap That

Also track tandems are 😍

Cool video, awesome bike!

Very nice.

Steel competition bike or just for training?

how do you adjust chain tension between the front chainring and the left back one?