This bike built by Edmund Polchlopek in France in the 1980's and used main tubes of MacSteel tubing. These butted steel tubes had .2mm-wall center sections lined with carbon fiber, and were originally designed for aircraft.
Diamondback would do something similar with their "welded carbon fiber" bikes in the 90's, but neither of these designs exposed the carbon to assembly heat applied near the ends of the tubes.
This bike has Tri geometry, so I don't ride it much, but has lasted over 30 years now and shows no unusual flex characteristics. I like that it has the elegance of lugged-steel construction, and was initially in disbelief when the seller told me it was a composite frame!
