nvilletele

Hi, I am brand new here, and am hoping to get some advice/suggestions on how to address non-functioning gear shift levers on an older (1995~96ish) Specialized M2 Pro Road Bike that I came into possession of recently.

My days of bike riding are pretty far back, and while I did a lot of riding at one time (35 years and and earlier) it was more for local transportation in high school, college and grad school than any long distance touring or racing (though I do recall once heading out from Davis, CA to Lake Berryessa that was a good trek, for me at least).

I used to work on my bikes myself, but these were ancient Schwinns (Varsity, Collegiate and Continental) that were really easy to work on and also, since they were built like tanks, hard to damage.

The problem with this Specialized road bike (which though old generally appears in good condition, and rides well) seems to be that when engaging the gear shifters, no tension is transmitted to the cables. The shifters move freely, but nothing happens. Holding the exposed cable part while engaging the shifter makes this clear, and when I myself pulled the rear cable while turning the crank, I was able to get the rear derailleur to shift from 3rd to 1st gear, so the derailleur itself seems ok. The front derailleur was already on the the large sprocket and I don’t know how to check it further, but it looks in good order, for whatever that’s worth. In any case, it seems pretty reasonable to assume the shifters are the problem since they clearly have no effect on the cables when engaged.

Looking at the shifter mechanism, I cannot see how to open it up or otherwise access inside. I expect there is some simple (?) way, but I don’t want to go mess with it before I know what I am doing.

The Components are as follows:

Component Group Shimano 600 Ultegra
Brakeset Shimano 600 Ultegra Dual Pivot brakes, Shimano 600 Ultegra levers
Shift Levers Shimano 600 Ultegra STI Dual Control
Front Derailleur Shimano 600 Ultegra, bottom-pull/clamp-on 31.8 mm
Rear Derailleur Shimano 600 Ultegra

I will upload some pics once I figure out how to do that (my first attempts here with my iPad were unsuccessful, though I usually am pretty savvy with such things).

I will appreciate any and all advice and recommendations, other than “take it to a repair shop” or “ask an experienced friend,” both of which I have already thought of myself. I may end up doing just that, but thought I’d give it a first stab myself, as sometime these things turn out to be easier than expected. It’s at least worth a try, I figure.

Thanks in advance for any help.

canopus 

A quick guess would be that the cables are frozen or otherwise no longer attached to the shifters or something in the shifter has broken. You will need to investigate the shifters and cables inside the levers. On anything that has been sitting for a while, depending on condition, i usually recommend replacing the cables anyway... My days of scrubbing a cable to make it shiny and pretty are getting further and further behind me but those STI cables are a little different.

The other things is use google search... it is wonderous...
https://www.bikeforums.net/bicycle-m...ti-levers.html

cxwrench

This happnes ALL THE TIME with Shimano shifters. Spray WD40 into the shifter where the cable goes in. Do NOT try to take it apart. Spray the WD in and shift it a bunch. They'll start to work again...it may take a while but they'll work.

nvilletele

Great advice. I got the shifters apparently working fine. The front derailleur works great now. However, I am still having some trouble with the rear derailleur, as even the the shifter seems to properly function, and I feel a tension now in the cable when I push the brake lever part to the side, the gear is not changing. I am wondering therefor if there maybe is an issue of some kind with the rear derailleur itself, maybe as simple as the cable tension but of course could be much more serious. (The rear derailleur turns out to not be the stock shimano 600 ultegra, but a shimano DEORE XT.)

I am hoping to find a knowledgeable friend to assist me in diagnosing the remaining issue. However, I do have an additional shifting related question I am hopeful someone can assist me on.

There is another small shifter of some kind on the diagonal part of the frame, close to the front yoke, on the rear derailleur cable, where the cable shielding ends and the bare cable begins. There are 4 settings possible. Can anyone help out an ignorant newbie and clue me in on its exact function? My only guess is that this is to access higher gear settings, but that seems also unlikely. Or is this part of the basic gear switching? Again, what do I know? (Very little).

Appreciate any and all kind responses.

woodcraft

Found this on Ebay

Shimano SM-ST74 Down Tube Housing Stops Barrel Adjuster Flat For Alloy Frame

cxwrench

Watch some YT videos, sounds like your cable tension is low. Art's Cyclery has a great channel. The adjuster on the right side of the down tube is an attempt by Shimano to make it easier to adjust cable tension (length). If you shift to an easier gear and the chain doesn't go OR you shift and get some noise because the cable is a little loose (long) you can flip the lever one click at a time to add tension. They're ok but I definitely prefer regular threaded barrel adjusters and their infinite adjustability.

curbtender

Most of the shifters come back with repeated flushing with WD40. The problem is that the lube gets into a varnish like state on the pins for the pawls. Along with the flush, let it sit in full sun to soften up the crud. Flick it repeatedly back and forth. When it clears out, get a good spray lube like triflo and spray it again.

icemilkcoffee 

I strongly recommend following this above guide to disassemble and clean your brifters. You can try to flush it without taking it apart but it doesn’t work nearly as well.

cxwrench

I strongly recommend NOT taking them apart. So does Shimano.