Shimano 100GS group (xx-M100) was made 1991-2. I know of no on-line docs for the group.
1) Wash out/soak the shifter with something like WD-40 until it works, then spray in a light lube if you have one. Exact procedures vary.
2) It's probably a matter of adjustment of the FD, but giving the left shifter the same treatment couldn't hurt.
Also check that the cables are smooth in the housings.
Thanks. I had a feeling that WD-40 was going to be in there somewhere. My two favorite tools on cleaning up a junkyard bike: WD-40 and compressed air.
I also had a funny feeling that this 100GS line was not exactly one of Shimano's majors when I did a search on eBay and came up with NOTHING
. By the way, thanks, you've also dated the bike for me. I was wondering what era they would have combined 100GS with BioPace chainwheels (which I thought had disappeared in the late 80's).
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Syke
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