Another poster who has tried it says Mapp/air and even Mapp/Oxy don't work. Likely experience or, more acurately, inexperience plays into it. If you have experience welding with different kinds of equipment you will spend much less time on a joint than a novice and will consume less gas and distort the frame less with overheating. I have spent most of my adult life being a musician and computer engineer. Lately the urge to build recumbents has hit. Like the o.p. I don't think welding is the way I want to go but I am going to come right out and say that I don't think that a course at the local community college is going to make a professional welder out of me and its one thing to put my own butt on the line but I will be building a tandem and putting my pretty s.o.'s butt on that line as well. The bamboo frames intrigue me but I grew up around bamboo. The dimensional stability and long term endurance of bamboo in a temperate climate does not impress me. I read somewhere though that in terms of tensile strenght and modulus of elasticity and what other terms you guys use to compare frame materials, bamboo and aluminum come out fairly close. I was already where another poster in this thread was with using aluminum instead of steel for the tubes. Where I would differ is in the use of carbon fiber as a lug material.
AFAIK there is a galvanic reaction when dissimilar metals are bonded. Apparently carbon fiber acts like a metal when put against steel and also aluminum. Most bamboo frames are lugged with hemp or sisal fiber and, although it is not a look that I really like, I wonder if hemp or sisal fiber in expoxy could not be used to bond aluminum tubes as well.
H