Go Back  Bike Forums > Bike Forums > Classic & Vintage
Reload this Page >

"RGF" French bottom bracket shell?

Classic & Vintage This forum is to discuss the many aspects of classic and vintage bicycles, including musclebikes, lightweights, middleweights, hi-wheelers, bone-shakers, safety bikes and much more.

"RGF" French bottom bracket shell?

Old 03-24-06, 12:42 PM
Old Skeptic
Thread Starter
stronglight's Avatar
Join Date: Jan 2006
Location: New Mexico, USA
Posts: 1,044

Bikes: 19 road bikes & 1 Track bike

Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Likes: 0
Liked 6 Times in 5 Posts
"RGF" French bottom bracket shell?

Can anyone offer info about the maker of a bottom bracket shell on a 1970s bike I recently bought. Bike has pure French tubing dimensions and French threading. The BB is fairly simple (no fancy feature-cuts like a Nervex Pro) and has "RGF" within an oval, cast/forged onto the top left side. The rest of the lugs on the bike appear to be a Prugnat "Professional" set with long spearpoints. I'm sure I had once seen this BB logo on another bike, but cannot now find an example on any of my other French bikes.
stronglight is offline  
Old 03-25-06, 07:39 AM
Dave Moulton
ex frame builder
Join Date: Aug 2004
Posts: 524
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 5 Times in 3 Posts
Iím 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 ďBulge FormedĒ 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. Iím sure the bulge forming process is still being used for lower end bikes.
History, photos and tech articles on "Dave's Bike Blog." 'dave moulton' Registry including a Picture Gallery https://www.davemoultonregistry.com/
Dave Moulton is offline  
Likes For Dave Moulton:
Old 03-25-06, 08:27 AM
Senior Member
Sluggo's Avatar
Join Date: Oct 2005
Location: Left bank, Knoxville TN
Posts: 622
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked 124 Times in 57 Posts
I believe the manufacturer is Gargatte. They also made (or still make?) investment-cast BB shells.
Sluggo is offline  
Old 03-25-06, 10:17 AM
Senior Member
Join Date: Feb 2005
Location: Pleasanton Tx
Posts: 1,214

Bikes: old,older.and very old

Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 31 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Somehow "EX" framebuilder does not sound right with "Dave Moulton"---but anyway I have that BB on a mid 50s Maclean,thanks for the insite on it.HarleyDavision uses this bulge process,they call it hydro forming,to make the bends on their new superbike frames because regular tube bending could not get the curves needed for the frame .
frameteam2003 is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell or Share My Personal Information -

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.