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My Tiagra 10-speed shifters have recently been jumping multiple gears. Shifting down (from smallest cog to biggest) is fine (10-9-8-7-6-5-4-3-2-1), though maybe a little stiff. But shifting up will jump in the middle (1-2-3-4567-8-9-10) with single pushes of the paddle casing the gears to crash up multiple gears in the middle.

I've ridden 20K miles (32K Km) on this bike. The shifter cable was replaced in May, about 250 miles ago (this is my winter bike), and the rear mech was new in February.

So I'm thinking maybe the shifters are just worn out?

Or should I just replace them?

Are the shifters serviceable?

Or could it be something else? I don't think it's cable tension as I'm shifting up fine - but I'm not a mechanic so...)

Thanks for any good advice.

  • This sounds to me like a sticky cable. – Daniel R Hicks Oct 25 '18 at 12:15
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That sounds like the shifter itself is malfunctioning.

If the cable or derailleur was hanging up you would get delayed multiple upshifts after clicking the lever several times, but you are saying that a single click results in a 3 sprocket upshift.

My guess is that the pawl mechanism in the shifter has worn and is slipping when upshifting, but is managing to hang on when downshifting. To confirm this you could try detaching the shift cable from the derailleur, putting tension on the cable manually (as close the shifter as possible if you have exposed shift cables, to eliminate cable or housing problems from the test) and seeing if you can get the shifter to slip when upshifting.

If the shifter is the problem, they are not serviceable. A replacement is necessary.

  • I've not described it very well but basically a single tap of the upshift paddle causes about 3-4 clicks up so I do suspect that it's ultimately wear and tear. But thanks for the idea - the cables are externally routed so I'll give your suggestion a try. – SimonH Oct 22 '18 at 14:15
  • The two most common reasons I've seen for something like this are either the grease in the shifter gumming up (but that tends to affect all the gears, not just a few like you're seeing) or broken teeth in the shifter that the pawls engage. That seems the most likely from what you're describing. Shifting the two directions (up vs down) usually engages different sets of teeth (or at least different parts of the same teeth) which explains why it works for you on downshift but not on upshift. – Noah Sutherland Oct 22 '18 at 23:51

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