Bertin road bikes in this period frequently had Simplex Tour de France, Cyclo or Huret derailleurs. Derailleur attachment could be bolt on or to dedicated stamped steel brazed in rear forkends. Front derailleurs were rod or lever/cable operated towards the end of the decade. Wheels were frequently 650B for utility and touring bikes but racing bikes used the larger 700C format. Lugged frames were the norm usually built from Vitus Durifort or, more rarely, Reynolds 531.
This is a 50s period Bertin C 10 with SA rear hub. Note the Ideale woman’s saddle and the brazed on centerpull brakes. From leboncion.fr, Oct.2009.
An unidentified but quality frameset from the period with stamped dropots including a derailleur tab.
Detail of dropouts
A late 50s or early 60s Bertin C 34 “Course Competition” built with Durifort tubing.
This Bertin C 25 “Porteur Parisien” from the late 40s or early 50s was found on leboncoin.fr in November of 2009.
This photo of a C 25 is also from leboncoin and was advertised a couple of times in early 2011.