I don't remember what started the search, but I ended up on the Bikeforums.net homebuilt Xtracycle page over the weekend..........if someone in Western Canuckistan can do it so can I!
I dragged two old steel frames together, in fact I tied them together so that they could commune overnight. Come morning things were looking good. I posted some pics on the thread, hoping for advice and encouragement, but after 30 minutes there was no response so I picked up the grinder and got to work. I mean hell, boy, what time do you wake up in that part of the world ;)
Fortunately (for my level of skill as a welder) these frames are made of steel, back in the days when it was still cheap. They made nice thick-walled tubing for sparkers like me to play with.
I think the extra few hours of thought paid off (as it so often does) and I was able to turn out an XtraCycle frame that rides pretty well (still no technical gubbins...brakes, shifter cables etc) without having to backtrack.
OK, the process in a nutshell:
Put the frames together to see how they work together (actually bolted the donor bike and the "other" bike (the receiver?) together, BB to dropout. That gave me an idea of what and where to cut.
Cut and grind. Removed the down-tube in it's entirety, kept the top-tube, but sliced it to facilitate a bend. Grind the front of the top-tube to mate with the receiver's seatpost.
Weld (yes I know you can't weld this stuff with an arc welder) That's why I just pretended I had a tig welder and got on with it. Looks not unlike pigeon shit, just smaller. Nothing that body-filler and undercoat can't tidy up. (Actually, I'm rather proud of my arc welding ability)
The "meeting point", where the donor bike's BB goes into the receiver's rear drop-outs was simple enough. A 12mm high tensile bolt, drilled dropouts to 12mm, some spacers, aligned the whole lot and welded it in place. Neat, strong, simple.
So far a fun project, the rack detail at the back is going to take more time, it needs a strong, lightweight, cheap, home-made, practical, stylish rack (I don't want to raise expectations at this stage).
So that's her, and yes, I know it's like coming out of the closet, here I am riding those little wheels aided by clickers and gorillas. Standards just ain't what they used to be. Please don't tell anyone.
OK, seriously now. That "parallelogram thing" looks like the business to me. This bike suddenly opens up a few possibilities, there's space to load quite a few litres of water in there (Sishen-Saldanha and another Bushmanland trip are now in reach.) Just a pity about those little wheels, but I could get over it. And the gears.
If anybody has any ideas about racks, please supply.