re: front derail. for TA cogs, was [CR]crane/suntour combo,


Example: Framebuilders:Chris Pauley

Date: Mon, 25 Oct 2004 20:27:48 -0400
From: HM & SS Sachs <sachs@erols.com>
To: mhoffman0@snet.net, classicrendezvous@bikelist.org
Subject: re: front derail. for TA cogs, was [CR]crane/suntour combo,


Mark Hoffman wrote:

<snip> I'm using a modern 105 front with a TA triple on Stronglight 49D cranks. Can anyone suggest a period correct front derailleur that would shift well with this set-up? (49/40/32)

Well, the very first thing, before anything else, is that the FD must have an absolutely flat outer plate. No dimples, creases, bulges, CPSC lips or anything else.

The second thing is getting the chainrings to run true, w/o wobble.

You see, getting the proverbial camel through the needle's eye is easy compared to getting the outer plate to pass between the outer ring and the crank w/o rubbing either, when you are climbing out of the saddle or whatever in the highest gear. It's the closest thing to an interference fit that you can see through, if you get my drift. How could a culture that celebrated "constructeur" bikes with full braze-ons tolerate this insanity? Were they so hung up about Q-factor or something? (Please don't answer that if it would start the Q-factor fires here, the only place I know that has been immune).

I've had decent results with the pre-CPSC Campy record (get the later one with body bulge for the outermost pivot, and circlip). Suntour Cyclone & Cyc. II are flat outers, with decent length cages (to clear the granny cog on several back rings). I don't think there is a stronger unit in captivity than the Shimano Titlist, but it has a very slight ridge on the outer plate. I used to take these apart and rearrange things to use on the curved-tube tandem. Required moving the pivot forward, extending the cage, changing the attachment angle, and adding a washer to space it out further from the parallelogram. Ugly but effective, sort of a Parody of Bill Boston's work on Campy REcords.

But I don't feel very strongly about this....

harvey sachs
mcLean va