Bertin graphics, in common with other bicycles in the period 1950 – 1990, underwent an incremental process of simplification and cost reduction. Gradually, over time, complex lug shapes, metal head badges, chroming, lug lining, pinstripping and contrasting frame paint panels all were reduced and then eliminated.
This process can be seen in the Bertins of the 1970s. The period was one of tremendous market growth in the early 70s and manufacturers simplified the product to speed production and increase profitability. The process was most noticeable in the lower price points where margins were slimmest.
There is no sharp distinction between late 60s and early 1970s production. Materials and finishes varied with availability and a typical early 70s bike looked very similar to its predecessors.
Sport and racing Bertins were usually found with the classic vertically 
stacked seat tube lettering and the foil World Championship stripes as seen in the photograph above. These stripes might also be found on the head tube wrapping around behind the
usual Bertin foil headbadge except on smaller sizes. Frames had the distinctive Made in France yellow riband (often on the top tube) and the A.B. diamond decal (often on the down tube). Mixte frames got both together on the down tube.In each of these respects the framesets did 
not differ much from earlier versions of the same model. Touring bicycles received the round Cyclotouriste decal which might be found on any of the three main frame tubes.
The example to the right shows on the down tube but other locations would be just as likely.
As the 1970s progressed, Bertin once again began to use the down tube for decal placement. The change was not wholesale and immediate but appears to have occured over time with decal availability. The sample C 37 below illustrates the general appearance of the graphics.
The style of the lettering can be more clearly seen in this down tube label.
The seat tube retained the commemorative World Championship rings as did the head tube. The seat tube also acquired a foil badge like that of the head tube as well as the TI-Reynolds frame decal. A 531 decal was also found at the top of each fork blade.
Reynolds transfers for French cycle manufacturers were always in French text. France, in the 60s and 70s, was Reynolds’ largest export market and the company went out of its way to provide specially drawn metric size tubing and French labels. The TI-Reynolds addition to the labels indicates a late 70s production as Tube Investments took over Renolds about 1977. This decal set can be found at the Cyclomundo store on Ebay.
Many other Bertin cycles in the 1970s were offered with the familiar Vitus Durifort tubing using decals of this type.
The seat tube decal was as shown below and to 
the right and complimentary decals were found on each fork leg much like the Reynolds 531 transfers on the C 37. As well, some models were built with a combination of Vitus 971 main tubes and Vitus 172 in the forks and stays which paralleled the earlier practice with the C 35 using Reynolds 531 and Durifort stays and fork. A good example of this is the mid-70s Bertin C 37bis which used Super Vitus in the main frame and Vitus 172 for the fork and stays.
There are anomalies in the graphics of Bertins and the
frameset shown below is one of them. The frame carries the downtube A.BERTIN of an earlier period with a yellow eagle preceding the name. Otherwise, the decals appear similar to the yellow C 37 seen above.
Decals seen on mixtes and non-sports bicycles varied slightly to accomodate structural differences like tubing locations and angles. Some bikes kept the early 60s pattern of tricolour band on the seat tube even as the Bertin brand moved foward into the 1980s.
Bertin Classic Cycles 