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Braze-On Front Derailleur Mounting Problem(9 posts)

Braze-On Front Derailleur Mounting ProblemTricone
Jul 19, 2001 8:15 AM
My frame has a derailleur boss requiring a braze-on type front derailleur. After fiddling with my D-A front derailleur and its position, I wasn't able to align it adequately to the chainring. I decided to have a LBS do the mounting and adjusting, only to have them call me stating that they couldn't mount it correctly because the "frame's boss wouldn't allow the correct positioning". They said to contact the retailer whom I purchased the frame from to address the problem. I'd rather not have to ship the frame back. (I bought the frame 4 years ago, and am only now building it up). Is there any other way to address this problem? I thought that either the boss or the derailleur cage can be "bent" by hand or with some sort of tool so that proper alignment can be achieved. However, the LBS didn't even suggest this option. Any ideas?
re: Braze-On Front Derailleur Mounting Problemgrzy mnky
Jul 19, 2001 8:55 AM
I'd find a local frame builder and get some expert advice. It begs the question though: what have you been using up until now?
re: Braze-On Front Derailleur Mounting ProblemTricone
Jul 19, 2001 9:40 AM
Litespeed Vortex is my primary bike. The frame I've referred to in this post will be a secondary bike.
Let me rephrase.grzy mnky
Jul 19, 2001 2:43 PM
What have you been using for a front der. until now on the bike in question? Trying to get an angle on why it worked before, but not now. Could be that it was very old and the "standards" of the bike industry have creeped a bit.

Bending a brazed clamp is pretty common - a medium sized {metric} crescent wrench and something soft for the jaws should do the trick.
Let me rephrase.Tricone
Jul 19, 2001 9:42 PM

Purchased the frame 4 or 5 years ago, but never built it up. It was hanging in my garage until recently. I'm in the process of changing out my fork on my primary bike. The fork has been at the painter's, who will be (obviously) painting the fork and also touching-up some chips on the frame. The fact that I haven't had my primary bike for 4 weeks had inspired me to build-up this other bike. So . . it never did have a front derailleur until now.
re: Braze-On Front Derailleur Mounting ProblemDave Hickey
Jul 19, 2001 10:00 AM
Before you try to change the bracket, are you using the washer supplied with the derailleur? There is a concave washer that goes between the screw and the bracket. I tried mounting a DA front derailleur without the washer and I could not get the alignment correct.
re: Braze-On Front Derailleur Mounting ProblemTricone
Jul 19, 2001 10:14 AM
Yes, the D-A washer (that is concave, allowing one to position the derailler) was being used. Still couldn't get it to align adequately. A friend who I just spoke with said it's just a matter of bending the boss and/or derailleur cage . . fairly simple to do.
Bend the bosszelig
Jul 19, 2001 12:02 PM
Since you're doing all the right things, it sounds like when they brazed the mounting boss on, it wasn't correctly aligned. Take a large pair of vice-grips (scary stuff but for once, the correct tool) whose jaws are big enough so that the flat bits at the end of each jaw cover either side of the bolt hole and so that the curved part of the jaw doesn't touch the inward curve section of the boss. Clamp it on (you can cover the boss with electrical tape to protect the paint/chrome)and then make the adjustment. Don't get crazy, it doesn't take much for the adjustment. Others may say I'm nuts, but I would not bend the cage as the boss itself is not aligned.
re: Braze-On Front Derailleur Mounting ProblemLogjammer
Jul 21, 2001 3:58 AM
I had this exact same problem with a Tommasini years ago. I was trying to install a Dura Ace front derailleur that would come out of alignment as you tighten the mounting screw. My solution was to try a Chorus FD. It fit the braze on perfectly and alignment was spot on.
Good luck.