Gargatte Brothers ("Raccords Gargatte Freres")
St. Etienne, France
"....I used them (RGF bottom
brackets) 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 chain stay 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. Iím sure the bulge
forming process is still being used for lower end bikes."
Dave Moulton, frame builder
by user wiel
to Classic Rendezvous Lugs and stuff