Originally Posted by top506
I get the basic idea: the levers are cammed to trim the front DR as the rear shifts.
Do they require a specific DR setup? Are they indexed or friction? I just aquired a frame with the top of the downtube mounting braze-on, and I like things that are a bit different.
Top
They're friction, like most everything from 1982.
This was a fundamentally flawed design, because it moves the front derailer inboard every time you downshift the rear. If you keep going up and down in back, eventually the front derailer will be too far inward to run properly on the big ring.
They'll work with any low-normal front derailer, after a fashion. The problem they were intended to solve was later solved by fine tuning the shape of the front derailer cage.
Bad news is that nothing else will fit that braze on. Good news is that the bikes these came on were otherwise super-quality frames, comparable to frames that sell for a thousand bucks or more today.
See:
http://sheldonbrown.com/japan
Sheldon "A Good Idea On Paper..." Brown
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