Mtn Bike thumb shifter problem (1 Viewer)

[EricG]

Hey guys - got the mountain bike out today. It's a gary fisher - about 12 or 13 years old. Anyway, the right shifter/rear derailer worked fine going down the cassette (higher gears/finger lever). But when I went to downshift with the thumb lever ... nothing. No significant resistance, though the return spring brings it back. I was going to start by lubing the cables and derailer pivots - but given that I don't feel anything, I doubt this will help.

Any ideas where to start? I've never torn into these new fangled gizmos - downtube friction levers are my state of the art

edit - FWIW, it's a Shimano STX component group

 

[wxm]

You should be able to tell whether the thumb shifter is pulling the cable at all. My guess will be not, and it may be time for a new one. Shifters at this age have seen its days, you may be able to get one with same speed at eBay (no need to match the model, just the number of speed and possibly the gear for the largest cog to be safe).

 

[mustardfj40]

I think what you have there is the Shimano Rapid Fire, not really the old thump shifter, it's hard to explain but it's really simple to adjust, here's some info how adjust it:

How To Adjust Your Rear Derailleur - Bicycle Tutor

 

[2mbb]

You should be able to tell whether the thumb shifter is pulling the cable at all. My guess will be not, and it may be time for a new one. Shifters at this age have seen its days, you may be able to get one with same speed at eBay (no need to match the model, just the number of speed and possibly the gear for the largest cog to be safe).

x2

You might be able to take off the cover place and reveal the shifting mechanism, then use a spray cleaner (I use brake cleaner), then a spray lube might get it working again.

Shimano has some more recent parts diagrams available on their web site, or you might try a google search of the actual model/part number for that shifter.

Shimano

 

[IdahoDoug]

I recall this happening with that shifter and it needs to be lubed/unstuck is all. You push the thumb shifter and all you're pressing against is the light return spring on the thumb shifter lever itself, right? I'm right, I know (heh). It's a pawl type mechanism and it's stuck IN. It's supposed to pop out and grab the part in the shifter that then pulls on the cable to pull the rear der toward the frame. But instead it's just grabbing air. Fire some penetrating oil into it - just freaking soak it. I recall there's a way to open it up, but if you go too deep parts will go flying around, so just minimally open it up, spray and give it a while to penetrate. Or a good shop will know how to do the same thing but quicker by opening it up further without losing bits.

Get that vintage beast out on the trails, I say!!

DougM

 

[EricG]

I recall this happening with that shifter and it needs to be lubed/unstuck is all. You push the thumb shifter and all you're pressing against is the light return spring on the thumb shifter lever itself, right?

Yea, that's what it feels like. Nice and smooth, but nothing there other then the return spring.

I'm right, I know (heh). It's a pawl type mechanism and it's stuck IN. It's supposed to pop out and grab the part in the shifter that then pulls on the cable to pull the rear der toward the frame. But instead it's just grabbing air. Fire some penetrating oil into it - just freaking soak it. I recall there's a way to open it up, but if you go too deep parts will go flying around,

Yea, that's what I've heard/am afraid of - open it up and all the clockwork pops out like a Wile E. Coyote cartoon!

so just minimally open it up, spray and give it a while to penetrate. Or a good shop will know how to do the same thing but quicker by opening it up further without losing bits.

Cool, I'll give that a try ASAP. The whole thing needs a going over really. I used to tear my bikes down to the frame and rebuild them every fall and they were always perfect. Just don't have that kind of time any more.

Get that vintage beast out on the trails, I say!!

DougM

Vintage! This is my "new" bike

Well, the tandem is probably newer (Cannondale off of Caigslist - not exactly sure how old), but that's just a knocking-around-with-the-kids bike right now.

 

[KliersLC]

I had that problem on an old bike once too. I don't remember the brand, but just like Doug said, a little penetrating oil will work wonders. The cable itself can't be broken because it allowed you to shift one way.