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I have a road bike with shimano front derailleur and dropped shifter. For weeks my front derailleur has been very stiff, requiring much force on the shifter to go onto the bigger ring, so the other day I decided to look inside the shifter. Presumably because of months of 'forcing' the shifter up a gear, the circular rotating bit of plastic which the end crimp of the gear cable slots into was pretty mashed up.

So I purchased a new shifter of the same make and model and installed it (new cable too), but shifting up a gear still takes a lot of force; actually, it doesn't shift at all now. I can move the derailleur directly with my finger and thumb, with what feels like not much effort - I say that with caution because I'm not sure how hard it should be to move it manually. But it moves smoothly at least.

I've clamped the cable to the derailleur, on the smallest rung, as tightly as I can but still no luck. Any ideas?

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    Did you replace the cable?
    – Daniel R Hicks
    Commented Mar 25, 2020 at 17:58
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    Break it down into individual parts - does the lever move freely? Does the cable slide freely in the housing? With the cable routed correctly does it still slide? Cable routing can introduce restrictive bends. You've tested that the derailleur moves by hand. If everything works well individually what is it about assembly that's different?
    – David D
    Commented Mar 26, 2020 at 13:21

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Did you replace the housing as well? It sounds like the derailleur is working fine and the problem is somewhere in between the shifter and the derailleur in the housing.

To fully diagnose the problem, you'll need to start at the shifter and work through each section.

First test just the shifter, disconnect the cable and remove the cable from the housing. Does the shifter move easily now? You'll need to pull a bit on the cable to simulate the spring tension from the derailleur.

If that is smooth, repeat the test with the cable in the next section of cable housing. Eventually you'll find where the friction is happening.

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  • Thanks for the suggestion! I didn't think of that and will keep it in mind in the future. It turns out that the problem in this case was something else (see my answer)
    – MattBurrows
    Commented Mar 27, 2020 at 13:36
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I figured out what the problem was. As per Fred's suggestion I checked every section of the cable housing, which revealed that the housing was fine. The issue was that I was feeding the cable into the front derailleur clamp in the wrong direction (anticlockwise instead of clockwise) - thus the cable fed in lower than it should have, reducing the moment, and creating extra friction with the cable rubbing against the derailleur cage.

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