Garth, it seems more logical to me that the circumference mismatch that you see is based either on a bent cage, or it's intended. If the seat tube is straight and its center is collinear with the BB center, I don't see how seat tube angle can cause what you see. Can you explain further?
Ken Freeman Ann Arbor, MI USA
-----Original Message----- From: classicrendezvous-bounces@bikelist.org [mailto:classicrendezvous-bounces@bikelist.org] On Behalf Of Bianca Pratorius Sent: Saturday, July 28, 2007 7:06 PM To: classicrendezvous@bikelist.org Subject: [CR]Have you ever done this?
Apparently some front derailleurs were made with a certain seat tube angle in mind. A touring triple front derailleur, I would guess, was designed with a 72 -73 degree seat tube angle in mind, and a racing double was designed with a 74 or even 75 steep angle in mind. When you attach a derailleur and tighten down, you can get the lip of the fd to not match the curvature of the chainwheel. Fortunately I have a braze on attachment so I fashioned a thin copper shim to go between the derailleur and the braze on tab, above the bolt that holds everything in place. When I tightened down on the allen bolt the derailleur changed it's angle and then seemed to match. This seems like a successful mod, (invisable, simple, reversible and cheap). Has anyone done this, or is there a better method I could have employed?
Garth Libre in Miami Fl USA