Braze-on derailler...how to



danmadone

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Mar 1, 2006
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Could someone please tell me what a braze-on derailler is. Is the other version a "bolt-on" derailler? How does one "braze" a derailler onto a frame? Thanks!
 
danmadone said:
Could someone please tell me what a braze-on derailler is. Is the other version a "bolt-on" derailler? How does one "braze" a derailler onto a frame? Thanks!

Two answers; some frames actually have a derailler mount, sort of a tab, brazed onto the seat tube. Many times a braze on derailer is used in conjuction with an adapter which bolts around the seat tube. This is often seen in oversized tubing. A bolton is one single unit.
 
danmadone said:
Could someone please tell me what a braze-on derailler is. Is the other version a "bolt-on" derailler? How does one "braze" a derailler onto a frame? Thanks!

Please see attached pics for the distinction. The brazed on derailer is mounted on a hanger. This hanger is 'brazed' (or welded) on a steel frame eliminating the need for a clamp. On carbon frames and even some aluminum ones this hanger is held by a pair of bolts or is riveted into the seat tube.

Note: Before luggless tig welded frames became fashionable, a bicycle steel tubes were joined together using investment cast lugs that were brazed - a welding process where brass or silver is melted to seep into the lugs holding the tubes via an acetylene torch. Investment cast front derailleur hangers were also 'brazed' into the frames.
 

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