Originally Posted by
zzyzx_xyzzy
I'm working on a homebuilt tandem frame using two donor frames for the front and rear triangles... what would you build if you were going from scratch?
You're not really going from scratch; you're starting with a couple of pre-built bicycle frames. Tandems that are actually built from scratch use tandem-specific tubing along with design experience in order to create that long stoker compartment without sacrificing rigidity and handling. Old tandems were built with short stoker compartments because the designers couldn't get the rigidity they needed with the single-bike tubing that was available. If you're using single-bike frames as the basis of your tandem, make the stoker compartment as short as you can get away with.