Originally Posted by
T-Mar
Based on the seat tube diameter, it wouldn't be Cromor. While Cromor is a double butted tubeset, it uses a single butted seat tube, with the butt at the bottom end. The wall thickness at the seat post end is 0.6mm. Consequently, it typically uses a 27.2mm seat post. A post diameter of 26.8mm would be typical of the plain gauge Aelle and Gara tubesets. 26.4mm is even smaller and down in the range of a lightweight hi-tensile steel. You should check the seat cinch slot for notable pinching at the top. Maybe the previous owner installed an under size seat post?
Very slow response but maybe some use.....I have a Carrera podium in the form of a Carrera 1. Seatpost diameter is 26.8mm and paint and stickers are original, they state 'Columbus' cromor on them.
I also have a Gitane Mach 340 GTX which has original paint and stickers, seatpost diameter 26.2mm. Original stickers state Columbus Cromor Custom
I also have a Motobecane Super Record 2, original paint and stickers identify it as Columbus SL. Seatpost diameter also 26.2mm
So, although Reynolds 531 has a seatpost diameter of 27.2mm, it is gas pipe compared to these Columbus frames. Maybe seatpost diameter is not necessarily a direct guide to the quality of the frame tubing.
Vintage Campagnolo Record seatposts appear frequently on e bay with diameters of 26.2 and 26.4mm. I'm pretty sure you would not have bought a gas pipe frame with one of these fitted to it.
Maybe Italian and French frame makers bought sets of these tubes and the seatpost only has a thicker wall at the stress point, ie where the clamp is located...