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Devolution is real!
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Discussion Starter · #1 ·
I bought a Giant ATX760, probably a 1995 or around that era. It has Avilo 7 speed trigger shifters on it. When trying to shift I push the trigger shifter to shift into a easier gear & nothing engages or happens 90% of the time. This also happens when trying to go to a harder gear. But sometimes the shifter does work & I am able to switch gears. I have taken the cover off & tried lubing it but nothing has changed. Is there any way to clean or repair a trigger shifters so it will engage again?
 

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Old man on a bike
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Old grease has probably hardened, spray a liberal amount of WD40 or similar in there to dissolve it while working the lever and then relube it (don't try and take it apart, use the opening for the cable).
 

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Devolution is real!
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Discussion Starter · #4 ·
Tried using some Slick 50 lube which is a nice lube (didn't work), but a degreaser might be the ticket. Is everyone pretty sure that the old hardened grease is causing the shifter to not engage?
 

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Bicyclochondriac.
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toyota200x said:
I bought a Giant ATX760, probably a 1995 or around that era. It has Avilo 7 speed trigger shifters on it. When trying to shift I push the trigger shifter to shift into a easier gear & nothing engages or happens 90% of the time. This also happens when trying to go to a harder gear. But sometimes the shifter does work & I am able to switch gears. I have taken the cover off & tried lubing it but nothing has changed. Is there any way to clean or repair a trigger shifters so it will engage again?
I have had this happen on an XT and Ultegra shifter, and it is starting to happen on one of the wife's LX shifters. I have found that once this starts happening, cleaning out and re-lubing may help temporarily, but basically they are worn out. I sometimes find if I push real slowly it is more likely to engage.
 

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Turn bike upside down and look for a little screw on the shifter pod to take off the cover, shifter in 7th gear. Now look and work the shifter see what is going on. Mine do this in the winter when the grease stiffens. The problem usually is the little metal spring latch that needs to catch on the indents on the round part not engaging. A few good spray's to clean it up with a rag underneth to catch the drippings. I use triflow spray so it acts as a lube aswell. If that don't do it it may be worn out.
 

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Yeah try lubing the shifters and seeing what happens. I have noticed on old shimano shifters that the main ratchet spring sits in a little plastic hole in the bottom of the housing. Over time this can wear a bigger hole resulting in the spring failing to either return properly or allow the ratchet to engage any teeth at all. Thats a good sign that the shifters simply need to be replaced.

The only way to tell is to open them up and see, but I wouldn't do it unless you know what you're doing. First time I did it I spent an hour figuring out how all the little parts went back together. I ended up fixing the shifters and my customer was very happy. Still a better set of 7 speed shifters are cheap as hell right now.
 

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I have found this to be a standard "feature" of Shimano shifters ever since the end of thumb shifter on the MTB and downtube shifters on the roadbike.

Anyone who as pulled apart a Shimano shifter can see the ratchet mechanism is a pretty light weight affair. Possibly why they make them non serviceable and charge so much for new shifters. It's a "consumable" like brake pads lol.

I’ve always found Shimano’s shifters to be the weak point in their otherwise awesome group sets (both road and mountain). I also have trouble believing they couldn’t make them more robust if they wanted. Then again I’ll freely admit I’m a very cynical person :p
 

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I just skimmed the posts so I'm not sure if it was mentioned, but I was having a similar problem with an older GT I restored.

I was going to try and fix that problem after I replaced the cables, but after I changed the cables the problem was gone. I took a quick look at the cable ball stops on the old cables and they were badly worn, which would result in the shifter mechanism only grabbing the cable every once and a while.
 

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Devolution is real!
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Discussion Starter · #11 ·
So the end of the cable ball (like in pic) was worn & replacing it with new cable fixed the problem? Interesting. Wouldn't think those ends would wear & if they did I wouldn't have thought shifting would be affected. I will try to lube the shifter again & then replace the cable if that doesn't work. Thanks for all your help.
 

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toyota200x said:
So the end of the cable ball (like in pic) was worn & replacing it with new cable fixed the problem? Interesting. Wouldn't think those ends would wear & if they did I wouldn't have thought shifting would be affected. I will try to lube the shifter again & then replace the cable if that doesn't work. Thanks for all your help.
Correct, that was my case though, yours may be due to something else. It's easy and cheap to replace cables though.

The cables that I replaced I suspect were OEM on the bike and thus over 10 years old. They can definitely wear out, in my case I suspect old age and corrosion to be contributing factors.

As to how they were causing the problems, the internals of the shifter grab the ball and pull on the cable to shift the derailleur. In my case, the ball stop was worn asymmetrically, thus the shift mechanism that would grab the ball to pull the cable would slide over the worn section most of the time. But as the ball stop was not fixed in place, it was able to move/rotate slightly and the shift mechanism would catch the unworn section every once in a while and shift correctly.

That is my best guess given the damage I noticed, the way the shifter operates and how the problem was gone after only changing the cable.

Needless to say, I rode the bike as a 3x1 setup for almost 6 months which was fun.
 

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Discussion Starter · #13 ·
That makes sense. Thanks for the write up. Worse come to worse & will buy new shifters. :thumbsup:
 
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