Bob wrote: << Fillet brazed (except the lugged fork crown) with a Marathon lateral between the headset and the 140mm rear dropouts. 26.6mm seat tubes, which I'm told is a mutt spec because a standard box-o-pipes tube set (from two of which a tandem was assembled) didn't have enough of the right sizes.>>
I sez: When I worked for Santana in the 80's, we specified 26.6 seat tubes on all Santana tandems (in fact, there's a good chance that your frame is made from a Santana tube set, as we sold them to many frame builders. The tube set was not a mutt, but was designed with a double-butted seat tube because of the heat stresses of the two top tubes (as was the Jack Taylor tandems). The Santana tubes were originally made by Ishiwata of Japan and later by Columbus of Italy.
Cheers,
Mark (tandemonium) Ritz
Arcata, California, USA
http://www.kinetic-koffee.com