rokrover

I was about to dismantle my Suntour “Symmetric” friction shift levers for cleaning when I noted a rather complex appearing internal mechanism and decided to leave well enough alone. These levers mount side by side to a housing bolted to the front downtube. They are linked inside the housing by some intriguing offset cam that, as far as I can tell, trims one lever as you move the other. Have I got this right? If so this is pretty ingenious and maybe well known to you old-time Suntour fans. The levers are 1983 or thereabouts, matched to Cyclone MKII derailleurs, but my earlier ’80 version has are totally independent levers and mounts with a clamp. One nice feature I miss on the new version is the “top normal” feature of the old; see: https://www.rivbike.com/webalog/shift...urs/17107.html
Wonder why this was changed.

luker

You're right, they are self trimming and work well for seven speeds, and a b!tch to work on. I haven't tried them on anything greater than seven cogs. I seem to recall that they made both "normal" and reverse front derailleur operation...I have a couple of sets, both of which are normal, so maybe my recollections are not accurate...

alanbikehouston

I have the "Symmetric" on a 1983ish Centurion Pro Tour 15. And, it is a nice feature. With most triples, it is difficult to avoid the chain rubbing on the gear changer cage at some point. the Symmetric moves the front cage as the chain moves from the smallest cogs to the largest cogs to avoid chain rub.

I remember someone posting about how easy it is on the 2004 Dura-Ace to "trim" the front cage to reduce chain rub. So, I suppose that means Shimano may now be catching up with the 1983 Sun Tour stuff.