The legend goes that Huret used steel rods in their iconic 'piano wire' derailleurs, because of the shortage of steel plate in post-war France. Here we have a patent, dating from December 1942, that shows two possible designs for one of the 'piano wire' models - the Huret Route Touriste. One design uses steel plate, the other the signature rods. Was Huret anticipating post war shortages? Possibly - but the text seems more concerned with generally economic and robust design than with the prospect of shortages of any particular material.
Browse associated derailleurs.
Huret Route Touriste 1946