Hi Don, This is what Dave Moulton had once told me about the RGF markings on the BB one of my own bikes:
" Bob,
I'm pretty sure RGF bottom bracket shells were made in France. I used them on most of the frames I built in England through the 1970s, and bought them from Ron Kitching who imported them along with the Prugnat lugs.
These BB shells were "Bulge Formed" which is an interesting process and I will explain.
A steel tube with the diameter and wall thickness of a bottom bracket shell is fed into a special machine. A mold clamps around the tube that has internal sockets that form the down tube, seat tube, and chainstay sockets. The ends of the tube are sealed and hydraulic oil is pumped inside. The pressure causes the steel to blow into the sockets like a bubble. The mold opens, the tube slides sideways to clear the mold and a saw cuts it off. The machine repeats whole process automatically. In a separate process the sealed ends of the sockets are machined off making the finished sockets for the tubes. Finally the BB shell is faced and threaded.
I used these BB shells because they were the best available at that time. By the late 1970s investment cast bottom brackets, which are far superior, became available. I'm sure the bulge forming process is still being used for lower end bikes.
Dave Moulton, Framebuilder, Retired "
BOB HANSON, ALBUQUERQUE, NEW MEXICO, USA
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