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My commuter bike has a 7-speed Tourney groupset with thumb shifters. When commuting today, I arrived at the office and shifted down a few gears before parking the bike as usual. I noticed that the rear derailleur was on the largest sprocket and didn't move on shifter input, anymore. I still had the clicks and the gear indicator moving but there was no action, the levers felt a bit light.

It is an older bike (bought in 2016), but since Tourney hasn't got much of a refresh, I think, it should be a ST-EF41-7R brifter, it looks identical to me.

enter image description here (Sorry for the bad photo)

I know that a snapped cable would drop the RD on the small cogs since there is no cable pull and it would fully retract into the high limit, but mine was stuck in the largest cog. I thought I had to ride home in a high-cadence workout but when returning to the bike a few hours later, shifting worked as expected, again. Trying all gears on the rear on the way home I think I once or twice got a louder click, as if some kind of rachet was just about engaging, rather than the usual "satisfying"/full sound, but no further skipping and normal shifts all the way.

It is a commuter bike and ~7 years old, I must admit that it doesn't get as much love as my road bikes, so the cables and housings have been replaced 2-3 years ago last and it does get its fair share of rain on my commutes, I haven't opened the shifter to see if there is some rust or gunk buildup, yet. Cables move fine and at least the exposed parts look pretty ok, no fraying or rust.

My guess is that the problem lies in the shifter internals and I should note that I rode into quite cold weather (-5°C) out of the garage and into rain the day before, so I suspect this could be related. Could a cable get stuck from riding approximately 30 minutes in those conditions, could water freeze in the housings?

I did have the issue only once, any I idea what could be the problem, how to further diagnose or to fix it? Does something need greasing/cleaning? I have a good collection of lubricants from WD-40, chain sprays, grease and specific chain lubes at home...

I've found this question that gave me the hint about water in the cable housings:

How to prevent shifting issues due to derailleur or cables freezing in cold weather

Update

I have added two videos following Criggie's answer, put a bit of lubricant in the rear derailleur's pivots but it certainly wasn't stiff before.

There is a little audible scratch when moving the cable but in warm/dry conditions, it moves OK, so does the rear derailleur:

https://youtube.com/shorts/EPzHpNHdYCE

Shifting is OK, too... chain was degreased when it shot the video and I tweaked the cable tension afterwards a bit.

https://youtube.com/shorts/LVT-LM7M3N0

(Sorry, it is hard to film when you've only got two hands).

So, it was definitely a temporary issue somehow related to the outside conditions.

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    I'd guess the commuter gets a lot more rain than the road bike. If you can store it out of the rain both at home and at work, that helps extend its life. Also, regular cleaning helps get the abrasive dirt/grit off the bike from wet-day rides.
    – Criggie
    Nov 29, 2023 at 22:26
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    Do your local streets get salted in the cold ? Salt rapidly accelerates corrosion, so only use stainless steel or plastic-coated cables in places there are salty roads.
    – Criggie
    Nov 29, 2023 at 22:27
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    The bike definitely gets its fair share of rain, at home, it is in a closed, unheated garage but at work, there is no convenient option to store it under roof cover or even inside, sadly. Salt is definitely used but I think too early as a cause this season, it was hardly freezing until now. I will check how everything moves and try to lube what I can externally. Good tip with proper cables, these will need to go at some point anyway, I was actually aiming to make it through the winter, at least if no problems occur.
    – DoNuT
    Nov 30, 2023 at 5:35

3 Answers 3

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I see a couple of potential issues that I've had on my bikes.

One is the grease in the shifter itself stiffening up in the cold. Applying spray oil might help, but do so when it's warm and operate the shifter repeatedly to work it in. It's tricky to get it far enough into brifters, but I've done it on flat bar shifters

The other is water in the cables. Yes, it does happen, and on your sort of timescale. I've had this with my rear derailleur, but it was much more disturbing when my back (cable disc) brake froze during a ride. My bike is kept in a frost free but unheated garage overnight, and the brake worked for a few minutes then froze rubbing slightly but no use for slowing down. It had been wet the day before. I fixed it by getting the cable housing really dry (heat plus blowing air through it) then fitting a new inner cable and packing as much grease as I could in there.

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Pull the exposed inner cable that goes to the rear derailleur. You should be able to pull it gently sideways while working the shifter and feel the cable tense or release a few mm of length.

Set the shifter in "high gear" which releases as much cable as possible. Probably the "finger click" not the "thumb push"

Then bend down and push the rear derailleur body sideways with your left hand while pulling on the same exposed wire. The RD should move sideways toward the wheel as you tension the cable.


Suspicions for the cause:

  • Rust in the cable housing add too much friction, stops the RD spring from pulling itself down to high gears/smallest cog.
    Solution: replace inner cable and outer housings.
  • Dirt/damage in the rear derailleur, too much friction for the spring to pull back to high gears.
    Solution: clean and lube, and/or bend straight, and if it breaks you needed a new one anyway.

I doubt the shifter is at fault here. The lever feels "light" because its not doing any work to pull the cable. I bet the exposed inner cable is a bit droopy somewhere on its run.

The shifter should have 6 clear clicks giving 7 resting positions. You can try blasting the inside with brake cleaner and lube in case there's some old dry grease or dirt, but they tend to cause different shifting problems to your symptoms.

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    Thanks! I'll go through these checks, I wanted to clean and re-lube the drivetrain anyway, so I'm going to make it part of that exercise. Except the last part of my morning ride the bike actually shifts fine (as good as 7-speed Tourney shifts) and the RD moves freely, it really seemed like a temporary issue but I will monitor on the next ride(s).
    – DoNuT
    Nov 30, 2023 at 8:55
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    Updated the question with some videos. Looks OK to me, the cable sounds a bit scratchy but it moves just fine, so does the derailleur. Mysterious.
    – DoNuT
    Dec 1, 2023 at 13:42
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I had that problem last winter when riding in -20C, with otherwise clean and relatively new drivetrain/cables. Fixed by greasing cables and derailleur joints with MucOffs cold weather lube (the one marked with -50C). The one that froze on me was FinishLine regular wet lube. (I didn't bother regreasing the chain though, only derailleur joints and the gear cable). Dunno about brake cables, I had hydraulics.

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  • Are there any alternatives like cable housing with special coating? I guess, I'd need to pull the cables out and apply lubricant?
    – DoNuT
    Dec 1, 2023 at 18:26

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