Join Date: Oct 2004
Location: Tampa, Florida, USA
Bikes: '69 Carlton Team Pro, '74 Raleigh Pro, '74 Motobecane Grand Jubilee, '64 Royal Enfield Revelation, '70 Raleigh Twenty, 2005 Carrera Delfino, 2003 Moser M81
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My experience with modifying the rear triangle leads me to recommend extreme caution.
The chainstays are tiny. A cold set will work, but for how long? The hidden
stress point or tube cracking may first appear near the rightside chainstay bridge. My frame failed at this
point, but it was an accelerated failure due to running a 7/8 speed narrow chain on a single
speed cog that preferred a chain with more width. Since I had no jockey wheels to accomodate
any chain slack, each time the chain tried to ride up on the cog, it popped. Until I folded it on driveside during an uphill sprint. I had not realized that the occasional popping was sending damaging stresses through the frame..... It's all repaired now and I'm back in action, but be careful what you do back there. I've chosen to keep the chainline in tight on the frame to reduce bending moments. I've also added a deraillleur mainly to accommodate some chainslack and remove trauma from the driveline. I'm using a 5 speed corncob and 117mm spacing.
Good luck, Retreau