Jay Sexton wrote:
"Doug, this may be more of a topic for framebuilders forum"
Jay, this information is probably more useful on the Classic Rendezvous list since we have stopped putting top of bottom bracket shell gear cable guides on frames (except for special circumstances) many years ago. The problem is that the front part of the front derailleur braze on comes to a point that concentrates the stress right there when honking on the lever if the shift is stubborn. This design fault will create failure in a certain percentage of cases even if it was properly brazed. All of a sudden you saw this design of cable guide disappear for mostly that reason. Well, their are also issues of heating the shell up again after the tubes are in place. Anyway by looking carefully at the position of the braze on's, it might give clues to evaluate the quality of the frame.
I was always strongly influenced by my 1969 Hetchins that had tubes that held the gear cables under the bb shell so that was my preference. Besides it was a little cleaner in looks as well as ability to clean.
The first time I remember seeing these Campy top-of-bb-shell guides was on the Masi my parents bought for me in Milan in Sept of 1972 (it's a V Masi so I presume it was made by Confente). It, of course, has the nice bend that takes the cable from the left side of the frame and angles it to the right.
When I went to Ellis Briggs to learn framebuilding, I was very curious how they got just the right bend in this boss that comes from the factory straight. I thought maybe their was a special mandrel or who knows what kind of complicated tool to bend it to have just the right curve. To my surprise, after Jack Briggs brazed one on to show me, he takes a small hammer and tap, tap, tap, it now has the right bend. It fact it bends pretty easy, it is possible to do it with your hands. Another fantasy of precision broken by practical methods.
This is one area I look to see how careful the builder was in putting on
braze ons. It is with some effort that they end up in the right place.
They should put the cable right in the center of the down tube and the
straight part of the boss should be parallel with the face of the bb shell.
In addition, getting the left and right bosses to put the cable the same
distance from the down tube is also a challenge. My framebuilding buddy
Jeff Bock from Iowa (who does truly beautiful work) made me a special bit
holder to hold them in the right place when brazing.
>From an insiders point of view, if I was a collector of American frames, he
would be on my top five list for sure. It is always a mystery to me why
quality of work is not enough to warrant desirability and value. Quality
and name recognition are independent variables.
Doug Fattic
Niles, Michigan