Calfee was showing this tandem that converts to a single bike.
It took a little while to get my mind wrapped around this one. My first few reassemblies resulted in a loose screw or two ;)
Wow, the braking system also flips between rim and disc brakes as you go from tandem to single bike. Now that's impressive!
It is two different bikes, check out the paint.
Cool exercise in what's possible, but would anybody really want one? If you can afford this bike, you likely can afford a regular Calfee, and a nice single bike, niether of which will have the design compromises necessary for this convertible.
Only use I could see would travelling where you wanted the ability to ride a single and a tandem and didn't want to bring 2 bikes. That would appear to be a very limited application.
I own one of the Calfee convertible tandems. The bike fits into one S&S 10 inch case (or 12 inch if you prefer) and one Tumi 30 inch suitcase. My existing coupled tandems (Litespeed and Lynskey Helix) both fit into 2 10 inch S&S cases.
I was giving this some thought and realized it could work out ok for the captain as a single, but typically not for the stoker to do the same due to frame size needs, ie: the front top tube length, stem, bar width and height, would all be wrong.
For the captain riding it as a single, the main issue I see is in using the stoker cranks for the single bike. If both captain & stoker use the same crank lengths, then great, no problem. However stoker cranks are often shorter than the setup needed by the captain. For example, I can ride with 172.5-175mm crankarms, while my stoker uses 170mm arms and no way I would want to use those... ie: I can't see myself climbing Mt. Ventoux using 170mm cranks! Awkward workarounds could be 1) pack an extra set of triple cranks, or 2) setup same-side drive and use a triple crankset (wider spacing than a double) for both riders - then move the captain's to the rear section for single riding. If you didn't care about the crankarm lengths, then you're good to go with all the components used on the tandem.
According to the report at RoadBikeAction.com, "This bike is valued at around $25,000".
I would bet the cost of this frame would fall between the two. Built up with Rolf wheels, Di2, and lightning cranks that doesn't come up to $25,000, but then again its RBA.