I checked the archives and the internet and couldn't find any answers to my questions.
Reynolds made light gage 531 tubing for many years. In the mid 70s they introduced a boxed set of 531SL light gage tubes.
Besides the light weight the 2 distinguishing features of these tube sets were:
1. The fork blades were the then new Continental Oval shape similar Columbus but different dimensions.
2. The chainstays had about 3" long shallow flats pressed in for wheel clearance rather the the crimps used on most standard chainstay from those days.
It looks like Reynolds 531P or Professional tubing was introduced around 1980. It was supposed to be the same as 531SL except for 0.1mm thicker chainstays.
I'd never seen a 531P frame up close until now???
Questions:
1. Did the 531P chainstays have the same wheel clearance flats as 521SL?
2. Was there any overlap in availability between 531SL and 531P?
I've recently identified a frame I've had for several years. It has Andre Bertin decals but a partial rattle can respray with maybe the original white color left as bands on the seat and down tube. It looks like whoever painted it also replaced the decals.
I figured out that it's about a 1983 Andre Bertin C79 frame with Shimano vertical rear dropouts and a boss for aero shift levers brazed on the top of the down tube.
It may have come with a Shimano Dura-Ace AX or 600 AX aero gruppo especially since Bertin was the importer/distributor for France.
The frame looks identical to the C80 model in the Bertin section of the CR website except for the paint and shift lever boss.
http://www.classicrendezvous.com/
I now own this frame too... :-)
Chas. Colerich
Oakland, CA USA