Never seen one of those before. You have a rare beast there. Not only does it break down into three tiny pieces for popping in the boot of a car but the ability to omit the middle bit and have the option of reasssembling a solo bike instead of a tandem is sheer genius. Imagine if you lived in a tiny flat. You could keep the bits in a cupboard and clip together a bike OR a tandem in seconds! Brilliant! I like the engineering behind it too, especially the levers for connecting the cables. Now then, I'm sure it flexes more than a Cumberland sausage but that's not the point is it. Genius is what it is. Quite old too and yet I doubt it's ever been copied. Any idea what the original make was?