I have braced my tandem. I have looked at every single photo of every tandem I can find, and tried to get my feeble brain to imagine what the stresses might be, and have examined my wife's Raleigh Lady Clubman, and have concluded that a mixte frame has so much going for it that it's worth a try.
I have also heard by e from Mr Knight of Rangiora, a tandemist until he had children when his tandem was retired. I expect when his children grow a little more and leave home he will get his tandem down and shortly afterwards Mrs Knight will divorce him. Anyway here follow his remarks:
Now then young man, I've just perused your tandem piccies and I am mighty impressed by how straight and aligned the top tubes and seat tubes are. This is most unlike you. Did you have help? I hope that you intend to brace that big open hole where the direct lateral tube isn't. The Direct Lateral Design is the best tandem design; you know this is true because my tandem is one and everything bike that I own is the best. Also I strongly recommend keeping the drive all on the right hand side if possible, otherwise you need to venture into tandem chainsets which may look like normal chainsets except that of the four cranks, three are reverse pedal threaded to normal. Both fronts and the left rear. Tandem chainsets are expensive. However a triple or quad rear chainset and a sync chain on the right will work well. Sacrifice high gears for low ones. You need low gears, lots of them. You will be slower on a tandem, best get this out in the open at the start. Lots of people buy a tandem and think they will be really fast, twice the output, same frontal area and all that. Unfortunately, it doesn't work out like that, tandems tend to average your separate speeds. If you are faster than Heidi, then she will go a bit quicker than normal and you will go slower than normal. Uphill you will be slower, much slower. Downhill you will be much much faster. And on the flat you will be about the same or maybe a bit quicker. I have lots of tips for riding tandems; we will discuss them shortly at great length. After you have examined my Campagnolo toolkit.
I have just read this to my wife, who immediately has just said ' Oh *uck, that's no good. I thought we'd have an easy life. You'd better get in training then.' (She says *uck quite often, as a matter of fact, but I never tell anyone because several of the people we know are Rotarians.)
Anyway Mr Knight is almost unkind in implying criticism of my brilliant welding and alignment and whatnot, and the only reason he isn't entirely unkind is because it is a factual remark. My welding is crap and so is my alignment, usually. And no I didn't get any help and the way it came out right was this: Pure Luck. The jig to weld was two bits of angle iron clamped very hard to the BB shells, the frames held together with a length of rubber inner tube. And my experience has always been that this is as inadequate as any other method I've ever dreamt up, and I fully expected to have to bend the thing afterwards - erm - that is to say, Cold Set it -and was astonished that this hasn't been necessary.
Note, however, that I do not afford this Blog the courtesy of close-ups of the welds. "Hmm, MIG welds aren't very pretty, are they,' is what Mr English observed once when he had spent too long examining one of my machines.
So now I have got out all my old chainrings and spiders and bless my soul, my head aches with trying to find two that will synch in such a manner as to please Mr Knight and earn his respect and regard and ravioli. (No, ravioli isn't the word I wanted. I suddenly felt in a thingy mood, where you try to use the same letter - wosscalled - alliterative.)