I know it's a tough one, but since I'm particularly fond of aerodynamic steel bikes I try anyway. As the title says, I'm primarily looking for a Columbus Air frame, with a 61 to 63 cm seat tube. I would consider other tubing brands, as long as the frame is properly "aero" and of the right size. Therefore, other gems such as Koga Miyata full pro aero, Tsunoda, Shogun, Araya, Mercier Formule 1, Lotus (super pro aero) or even a nice Motobecan Profil (3, not 2) would be considered. Let's see what, if anything, comes up.