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.
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alanbikehouston

My 83ish Centurion Pro Tour 15 has the Symmetric shifters and Suntour Le Tech changers in the front and rear. They do a good job of avoiding chain rub. As you move the chain from the largest rear cog toward the smallest rear cog, the front changer also moves outward slightly.

They are friction shifters. My Centurion has five cogs, but the friction setup should allow me to also use a rear wheel with six or seven cogs should I chose to do so. These shifters were introduced at exactly the wrong time: just before Shimano introduced indexed shifting on its Dura Ace group.

top506

Thanks Alan; Geezzz, that was quick!
Do you need the Le Tech DRs? Or will any upper range SunTour DR do?
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Sheldon Brown

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: https://sheldonbrown.com/japan

Sheldon "A Good Idea On Paper..." Brown

well biked

I've got an old Schwinn le tour, manufactured in late '84, so it could be either an '84 or '85 year model, with the Suntour Symmetric shifters. The bike has Suntour ARX derailleurs front and rear, and I've checked the date code on the Suntour components, they're from '84 also, and the frame also has the unique braze-on for the Symmetric shifters. I bought the bike at a yard sale to use as a parts bike for an '83 le tour I was building up. Turns out I didn't use the Suntour shifters or derailleurs on the '83 bike, but I've been wondering about these shifters for another build, but I had heard they were a little different than conventional friction shifters. I hadn't thought about needing the unique braze-on to mount them to the frame, I guess they'll stay on the '84/'85 le tour frame until I build it up again. Thanks for the info-

cyclotoine

speaking of unique braze ons... shimano 600 friction shifters are different on my 85 norco than my other bikes, very upsetting that those have to stay on the bike, switching drive train to suntour cyclone for asthetic purposes and suntour freewheel abundance in my parts bin.

top506

Sheldon;
Thanks for the informative reply.
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