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Can I use hot water to unjam my Shimano trigger shifters? Has anyone had any experience with this?

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  • Can you describe how they got jammed in the first place? Without knowing the cause it's very difficult for us to know if hot water is a viable solution.
    – Andy P
    Commented Mar 29, 2018 at 9:02
  • I bought a second hand bike: I assume they've got stuck because the lube has dried out
    – Jeremy Feng
    Commented Mar 29, 2018 at 9:07
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    It might work temporarily. Generally a spray lube is the more effective and long-lasting solution.
    – Daniel R Hicks
    Commented Mar 29, 2018 at 12:23
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    If they're gummed up with old grease, open them up, remove what muck you can and add a light penetrating oil. Let it soak in/work it in. Repeat a few times and they'll be much better; finish with some light grease. If the cause is something else, open them up and sort that out.
    – Chris H
    Commented Mar 29, 2018 at 12:24
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    Possible duplicate of STI shifter sometimes doesn't catch in cooler weather
    – mattnz
    Commented Mar 30, 2018 at 2:18

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It could hypothetically help get them working, but at that point you'll have washed out a bunch of whatever lubricant remains and should replace it with something anyway.

When they stop working, the most common problem is that the grease around the pawls has gummed up, keeping the pawls from being able to spring up into their extended position where they can catch on the toothed ring. The first thing to do is remove the cover (don't disassemble them any further than this), find the pawls, drip some oil (whatever you use on your chain is fine) around them, and work them back and forth with some kind of pointy tool. The vast majority of the time, unless there's a broken spring somewhere that renders them non-fixable anyway, this approach will fix them.

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    WD40 is great for this.
    – Andrew Henle
    Commented Mar 29, 2018 at 15:31
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    When using wd40 just use the shortest spurt possible and try to work it on using your triggers. If you shoot in too much you risk flushing out all the lubricant and WD40 is a horrible lubricant by itself.
    – RoboKaren
    Commented Mar 29, 2018 at 16:24
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    WD40 is terrible long term, but its fine to dissolve the clagged-up grease, and see if its worth doing a teardown or not.
    – Criggie ♦
    Commented Mar 29, 2018 at 20:57
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At bikex.org, boiling water has been far more reliable than degreaser. We've had many gummed up shifters and the hot water works faster on old really old grease than (citrus) degreaser. Even the chemical degreasers haven't worked as well.

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    I'd worry that the temperature may upset some of the plastics - specially if they are old and brittle. Perhaps 60 degrees C would be better than boiling ? Welcome to the site - good first answer !
    – Criggie ♦
    Commented Nov 22, 2020 at 6:55

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