Either that or the Bi Titanio. Tony Rominger rode that frame--possibly during his win in the '95 Giro d'Italia, or perhaps the year that he stood to the right of Miguel Indurain on the podium at the Tour. Possible both, but I don't feel like digging through my VCRs right now.

As a designer Ernesto Colnago had an almost fanatical desire towards innovation, in eliminating power loss due to frame flex. Look at the number of custom proprietary tubesets he had designed and manufactured by Columbus over the years, made especially for his own marque. I know that the Bi Titanio, a frame I lusted but couldn't afford, did for a time have some durability issues. Who knows, it could have been that the double downtube was a strategy to overcome the lack of an easily available variety of appropriate shaped tubing, something that is easily available today but not so much back then? On the other hand, style and esthetics have always been a strong element that he incorporated into all of his top frame designs.