The mechanism inside one of my gear shifters is a bit skewiff and I can't lock the cover on properly. Any idea what the problem is? Pictures of the dodgy one and the ok one for comparison with the cover off and then on.





I think a part may be missing from the dodgy one?

Dodgy one:


OK one (with an extra cog?):


  • Hard to distinguish how each picture relates to the others. I can't figure out what you mean by a part missing or an extra cog being present. The first picture seems to show a coil spring that is mispositioned. Do you know what model the shifters are? Sep 16, 2018 at 16:49
  • 2
    Pic 1 and 2 are the same, as are 4 and 5 Sep 16, 2018 at 16:59
  • 1
    What is the model of the shifter? Have you tried looking up its schematics on the net? Sep 16, 2018 at 17:00
  • Note left and right are mirrors, but not identical due to the number of detents. So the right/rear shifter may be quite different on the inside.
    – Criggie
    Sep 17, 2018 at 3:39
  • While I totally owould try and fix these, if there's a part broken/snapped its easier to just replace the whole mech. Shifters are reasonably cheap.
    – Criggie
    Sep 17, 2018 at 3:42

2 Answers 2


This appears to be an EZ-Fire type shifter. Shimano or copy-cat. One model number is ST-EF29. That spring is misaligned and you'll need to get that seated properly. Then I suggest a good dousing with WD-40 or equivalent and exercising the shifter repeatedly. You may need to use a toothpick or the like to scrape out old grease and dirt. After cleaning, follow up with some sort of wet lube and work the shifters again. I've linked to a video showing some work being done on a very similar shifter to yours. Typically I don't find these types of shifters "broken" but rather gummed up or pieces disconnected like your spring. It's common for the junction to the gear indicator to be disconnected and/ or the little plastic connection broken. This doesn't affect the actual shifting just the gear indicator.
You have a good chance of getting this working sans the "dodginess."


To me, it looks like the spring 'jumped' out, occupying space and causing the nut on the top to unscrew itself. Not sure, i'm not a bike mechanic but maybe try unscrewing the nut, remove the washer and carefully place the spring back in and reassemble everything back. it MIGHT work, but don't trust me that much. I'm just suggesting you to try it, we might help you better if you provide us the model of the shifter because we might able to find the blueprint of the shifter.

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