Bicycle Tutor

My old mountain bike has Shimano thumb shifters. The front derailler will shift to the larger chainrings, but springs back onto the smallest chainring if I let go of the shifter. Any advice? Thanks.

Look at the top of the shifter and see if there is a screw or a flat ridge you can grab. If so, tighten these down so that the shifter will still move, but doesn't slip back to the small gear by itself. If not, maybe picture or model # of the shifter would help.

(Jul 24, 2012 12:56 PM)DaveM Wrote:  Look at the top of the shifter and see if there is a screw or a flat ridge you can grab. If so, tighten these down so that the shifter will still move, but doesn't slip back to the small gear by itself. If not, maybe picture or model # of the shifter would help.

---

Thanks. They are Shimano Diore XT model shifters, and on top there is an allen nut, but it seems pretty darn tight. I can try to tighten it a bit more. There are a couple of screws on the bottom/side, but they seem quite secure and didn't seem to affect anything. But thanks for your suggestions. I'll keep playing with them!

let me see a pic of your thumb shifters

Thanks - I have to leave town this morning for a trip, but will continue on my return (getting a picture posted takes some thought for me - I'm not hugely tech savvy).

Picture of the top and one picture of the bottom, save both pictures to your desktop. When you click on the "new reply" button on this site scroll down there is Attach Picture or attach file, after you click that a menu will pop up and then you can navigate the menu to your desktop and find the name of the picture, click once on the name of the picture and then click ok.Then click Post reply. That simple.

Sorry about the hiatus - I've been out of town. Here are a couple pics of my old front derailler and thumb controls. Again, the front controls will get the derailler to the larger two chainrings, but it springs back to the smaller ring as soon as I let go of the trigger. Any suggestions of how to get this to work again? Thanks. Kay        

Hi Kay;

Your shifter looks like a trigger shifter; not a thumb shifter.

http://www.interlocracing.com/shifter_thumb1.jpg

Trigger shifters are far more complicated.

(Aug 15, 2012 01:22 PM)nfmisso Wrote:  Hi Kay;

Your shifter looks like a trigger shifter; not a thumb shifter.

http://www.interlocracing.com/shifter_thumb1.jpg

Trigger shifters are far more complicated.

Thanks. Should I take it to someone or is it not worth even fixing?

---

Thanks. Is it worth fixing, i.e., paying someone to do it? KD

Kayd, update your bio and tell us where you are from, I may have parts. tell us the model number of your shifter. it is hard to see and under by the levers. they appear to be Sti push push style and not trigger.
I f you are in the us and will pay shipping I will have a look for you and may have spare parts to get you going again.

The factory grease may have stiffened up over the years to the point that the springs that work the pawls are not letting them engage. I took my shifters off the bike and soaked them in Simple Green for a couple of days and that fixed it. Then I found out that WD40 applied generously through the cable cap or other similar entry (without taking the cover off) will cure the same issue. Worth a try...

Thanks. I'll give it a try.