Left STX Shifter won't shift to largest chainring
 

The bike is an older Trek 7000 with Shimano STX shifters. The problem is with the left (front) shifter. The derailleur shifts into the large chainring with no problem when I tug on the cable, but the indexed shifter won't click (or pull the cable enough) to move the chain to the large chainring. It clicks for positions 1 and 2, but not for 3. Also, the indicator that's supposed to show what gear you're in doesn't move.

Is this fixable? If so, how?

Thanks!

Seems like you need to adjust for stretched cable.

Try taking the tension off the cable- shift to where the chain is on the big chainring and then stop pedaling. Click the shifter down to the index for the small chainring. Use the chain to hold the FD up on the large chainring. There should be slack in the cable. Slide the housing out of one of the stops on the frame.

With the cable loose, try and shift, if you can get the shifter to index in all three positions (keeping the cable taut with your right hand while you shift with your left), you might have an issue with the limit screw limiting the travel of the FD just enough that you can't get the shifter to click into the index for the large chainring. If you can't get it to click into the tightest index, then you could try spraying WD40 into the shifter through the straw on the can to see if you can loosen up the pawl that isn't moving freely anymore. If WD40 fixes it, be sure to wait a day or two for the WD40 to evaporate and then follow that up with some lubricant of your choice.

shifter saver. i have had good luck with liquid wrench

I did that, but it didn't help - it still won't click.

Post #3 then

If you "adjusted" for a stretched cable with a screwdriver, you've done it wrong.

No, I used a 5mm Allen wrench to loosen the cable at the derailleur, and then took up about 1/4" of cable and re-tightened the screw. Was that the right thing to do?

At that age, the most common issue is that one of the pawls has a gummed-up pivot. You can try the blind method of firing WD40 into the shifter repeatedly, or remove the cover, locate the gummed-up pawl, and target it with your WD40 while manually pivoting it with a toothpick or whatever, until it snaps back quickly when released. After that, I suggest oiling it with TriFlow or another light non-vegetable-based oil that won't gum up over time.

How about the rest of my advice? Can you get the shifter to lock into all three positions with the cable free to travel?

Edit: yes, either that or use the barrel adjuster on the shifter itself.

The limit screw isn't the problem - it shifts onto the big chainring when I operate the cable directly. I did try the "blind" WD-40 approach, without success. I'm going to try to open it up and free the stuck pawl with a toothpick + WD-40 after work today.

Thanks to everyone for all the suggestions.

Can you get it to click into the index for the large ring with the cable slack?

Help me help you buddy.

EDIT: and the limit screw could be the problem- just because you can shift the chain there, doesn't mean the shifter can get the chain there its pawl into the index for that gear. Now that you've tightened the cable, you might be able to swing the FD up, but the shifter needs a little over run to get the pawl to engage. You know how you need to pull a pretty good amount of cable before the shifter clicks? Well, with a tighter cable and a limit screw, you could be moving the FD all the way to the limit screw before you get to the click- thus, you're operating within that pretty good amount of cable pull and not letting the shifter get a full swing.

Two lessons learned here:

1) Never assume that I know better than people who have actually done what I'm asking about, otherwise, why bother asking?

2) I have a new best friend. :D

It worked! Thank you very much for the help, and I'm sorry for being obtuse. I guess now I give the WD-40 a couple of days to dry, then squirt in some lubricant?

Good man. So what was it? You over adjusted and the shifter couldn't get enough swing?

I had a feeling some of the tri-state attitude would jog the listening skills ;)

Yeah, lube it up, but don't worry about staying off of it. Ride it, but remember to have it lubed by friday the 13th.

The limit screw was definitely part of it. What wound up working was re-loosening the cable at the derailleur, then testing the shifter with a slack cable to see if it clicked. When it did, I realized that you were right about the limit screw, so I just went through a basic set-up for the cable and the limit screws, then did the finer adjustment with the barrel adjuster. The shifter was still a little sticky, so I really doused it in WD-40 and worked it back and forth until it moved freely and the lever returned crisply on its own without having to be helped with a thumb. It's shifting nice and smooth now.

Yeah - my tri-state attitude is compounded by having been born and raised in NYC, and then moving to the heart of Sopranos Country in my 30s. Fuggedaboutit!