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Old 01-31-10, 12:44 AM   #1
vredstein
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STX 7-speed shifters not working

I have a customer who brought in a bike that has Shimano STX 7-speed shifter/brake levers.
It shifts up and down from the small ring to the middle ring fine, but it won't shift from the middle ring to the large ring. The thumb lever will move, but with little or no resistance, and no cable movement. The problem is all in the lever. There's no cable obstruction and the limit screws are not stopping the derailleur from it's full range of motion. I've spraying the inside with Triflo. This makes the small to middle ring shifts crisper, but does nothing to fix the missing shift. I'm hesitant to start taking out screws or the bottom nut. I know some of these shifters have a tendency to puke springs and gears once you open them up.
Any advice?
The rear shifter has a problem also. It will shift up the cog fine. But shifting from the big cog down has problems. While in the big 7th cog, activating the trigger shifter one click moves the derailleur direcly down to the 5th cog, skipping over the 6th. One single click from there moves the derailleur down to the 3rd cog, skipping over the 4th. One single click from there moves the derailleur down to the first cog, skipping over the second. Again, there's no cable obstruction.
Are both these units shot?
The only replacement I can order with a cantilever brake compatible lever is an Altus 7-speed. Other than the shifters, the bike is in excellent condition, smooth bb, headset, good condition hubs, cassette, chain, true and even-tensioned wheels.
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Old 01-31-10, 01:19 AM   #2
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Sounds like a sticky pawl. The only true way to deal with that is open it up, degrease it with a clean tooth brush, and then lube it with some triflo or equivalent. Integrated STI shifters are really the only ones that puke springs. Most shifter generations have a removable outer dust cap/body that you have to remove to get to the insides--- so there's no risk of causing it to fall apart.

Once you have it open, there are typically two pawls that engage the gear (to form a rachet in both directions). Those pawls have small springs engaging them. You can use a small pokey tool or a small flat head to lift up the pawl and watch it return. If it doesn't return or is very slow, there's your problem. Degrease and re lube. I have this theory that most shifters fail around the winter time because the sun and heat in the summer keeps the goo nice and fluidy. In the winter, it gets gunky and chunky and fails.

BTW, dry slide is by far my best friend when it comes to shifter problems. So get some!

-FTU
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Old 01-31-10, 01:27 AM   #3
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Quote:
Originally Posted by vredstein View Post
I have a customer who brought in a bike that has Shimano STX 7-speed shifter/brake levers.
It shifts up and down from the small ring to the middle ring fine, but it won't shift from the middle ring to the large ring. The thumb lever will move, but with little or no resistance, and no cable movement. The problem is all in the lever. There's no cable obstruction and the limit screws are not stopping the derailleur from it's full range of motion. I've spraying the inside with Triflo. This makes the small to middle ring shifts crisper, but does nothing to fix the missing shift. I'm hesitant to start taking out screws or the bottom nut. I know some of these shifters have a tendency to puke springs and gears once you open them up.
Any advice?
The rear shifter has a problem also. It will shift up the cog fine. But shifting from the big cog down has problems. While in the big 7th cog, activating the trigger shifter one click moves the derailleur direcly down to the 5th cog, skipping over the 6th. One single click from there moves the derailleur down to the 3rd cog, skipping over the 4th. One single click from there moves the derailleur down to the first cog, skipping over the second. Again, there's no cable obstruction.
Are both these units shot?
The only replacement I can order with a cantilever brake compatible lever is an Altus 7-speed. Other than the shifters, the bike is in excellent condition, smooth bb, headset, good condition hubs, cassette, chain, true and even-tensioned wheels.
Here are your options.

Charge $60/hour and try to attempt to overhaul the shifter, or sell him a new 7 speed shifter set for < $20 MSRP. Also note most 7 speed combo lever/shifter units can have the shifter pods "deleted", and a seperate, shifter only unit installed - which your shop should be able to *easily* source.

We have done this mod in the past many times, and you cannot even tell that there even WAS a combo shifter/lever unit on there previously.
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Old 01-31-10, 09:23 AM   #4
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Shoot a bunch of WD-40 into the shifer and work the levers to up shift and down shift. Spray in more WD-40 and repeat maybe a few more times. If it is a sticky pawl that should get it loose and all will be good. I have used this method on a dozen similar Shimano brake/shift units (mostly mountain but a few times with road brifters) with great results.

The mid-90's Raleigh mountain bike I ride had a similar problem when I got it about 3 years ago and everything is still working fine, save for needing to do the WD-40 thing again late last summer when a few of the rear shifts had gotten a little balky.

If the WD-40 does not work you can be really sure the unit needs replacement.
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Old 01-31-10, 09:14 PM   #5
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Originally Posted by FasterthanU View Post
Sounds like a sticky pawl. The only true way to deal with that is open it up, degrease it with a clean tooth brush, and then lube it with some triflo or equivalent. Integrated STI shifters are really the only ones that puke springs. Most shifter generations have a removable outer dust cap/body that you have to remove to get to the insides--- so there's no risk of causing it to fall apart.

Once you have it open, there are typically two pawls that engage the gear (to form a rachet in both directions). Those pawls have small springs engaging them. You can use a small pokey tool or a small flat head to lift up the pawl and watch it return. If it doesn't return or is very slow, there's your problem. Degrease and re lube. I have this theory that most shifters fail around the winter time because the sun and heat in the summer keeps the goo nice and fluidy. In the winter, it gets gunky and chunky and fails.

BTW, dry slide is by far my best friend when it comes to shifter problems. So get some!

-FTU
This was the problem. I removed the bottom nut and the cover, took a sharpened spoke and worked a pawl up and down. It was slow at first, but a minute of working, blowing the unit out with compressed air, and it was springing back with life. Same deal for both front and rear. Took about 10 minutes and charged the guy $15 labor. He was happy.
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Old 02-02-10, 12:50 AM   #6
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Awesome!

Awesome! Advice that worked! And we saved a perfectly usable set of shifters from going to the dump! Sweet! -FTU
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Old 02-02-10, 04:26 AM   #7
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Awesome! Advice that worked! And we saved a perfectly usable set of shifters from going to the dump! Sweet! -FTU
I'll check out the Dri-Slide. To be honest, I'm not sure how long or well the Tri-Flow lasts, whether it will age well or gum up in short order.
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Old 03-30-14, 01:29 PM   #8
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Old thread, but it helped again. Kroil works fine too.
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