RGF Bottom Bracket Shell
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Main Photo
Photo Credit: VeloBase User wiel
Name: RGF Bottom Bracket Shell
Brand: RGF
Category: Lug Set
Model: Bottom Bracket Shell
Country: France
Years: 1970-1980
Added By: watsondm on 02/18/12
Updated By: wiel on 02/20/12
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Details
Lug Point CategorySeat Stay Arrangement
Avaliable AnglesManufacturing ProcessBulge Formed
General Information

RGF Bottom Bracket Shells - not uncommon on 1970s bikes.  Mine came with a 531 DB frame and fork with Campagnolo dropouts.  Interesting process, explained by "Dave Moulton" on BikeForums as follows..."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 for the benefit of those who have not heard of this.  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."

I have added better pictures of these brackets. It was common at Raleigh SBDU to make the brackets lighter by cutting 4 slots into the bottom, and that is where these brackets come from (updated by: wiel).

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