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Old 07-17-19, 10:22 PM
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scarlson 
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Join Date: Jun 2010
Location: Medford MA
Posts: 1,777

Bikes: Ron Cooper touring, 1959 Jack Taylor 650b ladyback touring tandem, Vitus 979, Joe Bell painted Claud Butler Dalesman, Colin Laing curved tube tandem, heavily-Dilberted 1982 Trek 6xx, René Herse tandem

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Originally Posted by t_e_r_r_y View Post
make me a clamp on one, please!
So I had already been thinking about making a clamp-on version, because my Jack Taylor lacks anything remotely original in the front derailleur department. The thing to do is to braze the square tubing to an oversize tube cut from an old MTB, braze in some clamp bolts, and bob's your uncle, as they say.

It would be nice if someone would mass produce one. I hear all the time that people want things like these, Nivex rear derailleurs, dropout chainrests you can shift onto, the list goes on. BQ readers want to be like Jan! I suppose the problem with this design is that it requires custom filing the slot that the handle goes through to your particular "throw" distance. This becomes your "limit screws" of sorts. A screw based limiter could be attached, but it's more steps and more complexity.

They are really hard to make. I wanted the derailleur to be all stainless to avoid necessitating any hydrophobic rust protection (oil or grease), which would attract dust. The stainless square tubing I could find in a decently robust wall thickness said it would fit my 3/8" square inside. However, when I bought it, I found that it has a visible welded seam running down the inside. This meant a lot of file work to remove the weld, which was also harder than the base metal. This was drudgery. Eventually I also filed down the pushrod a bit.

I have to think that René Herse must have used a square broach to make this hole the proper size and uniformly square so he could use milled square stock. I could too, and it would make cleaning up the inside of the tube really quick and easy. But square broaches are expensive. I think I'd be paying between $50 and $100 for a used one, making it the most expensive cutting tool I own, although it's a monotasker. Doesn't feel good.

I've got other ideas, too. We have a waterjet cutter here, so if I had any kind of measured drawing of a Nivex derailleur I could make reproductions. It's only stamped sheet metal after all. Ironically, that will probably require less initial investment in tooling than mass-producing this thing would!
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