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I have a Specialize Roubaix that's about 10 years old with the Shimano 105 component set. I've started to develop a problem in the rear derailer where when I shift to a higher gear/smaller cog, the shifter "jumps" multiple gears. Happens whether I'm on the middle or big chainring in front. And yes, I know it's jumping multiple gears because it takes multiple shifts to get back into the gear I started from.

This seems to be the opposite of the stickiness most people complain about. :) Any ideas on how to address it, short of replacing the shifter? I've already replaced the cables, adjusted shifting, checked the chain for wear, etc.

  • has this happened suddenly or do you think something might have just worn out? – PeteH Oct 4 '14 at 6:55
  • Pete, seems like it's come on gradually, so something wore out. – dpassage Oct 4 '14 at 21:24
  • In that case you only really have a few variables. My gut feel is that either the derailleur got bent, or you haven't adjusted it properly, or you haven't fitted the new cable properly. (But I don't want to criticise your workmanship!) You can test the shifter standalone, but you'll have to disconnect the cable first - simply check that it is pulling and releasing cable as you click through the gears. But there's not a whole lot more going on. – PeteH Oct 5 '14 at 8:18
  • Did you replace the cable outer at the same time? If there's damage to it it might cause this problem even with new cables. – Holloway Dec 4 '14 at 11:10
  • Trengot, the effect occurs when there's no housing involved at all, just my hand pulling on the bare cable against the force of the shifter. – dpassage Dec 4 '14 at 20:37
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Often, this is a problem with derailleur adjustment, so I'd double check and triple check that first.

The first thing to do is check if the rear derailleur is bent. If it is, get it un-bent - it is near impossible to adjust a rear derailleur which is bent adequately. The second thing to make sure you have adequate cable tension, proper cable installation and your derailleur is adjusted properly. Here are some good directions on doing that (as well as here).

Assuming your cables are installed properly and you've adjusted your derailleur correctly (and as correctly as possible) and your chain+cassette aren't worn, then I'd start by replacing the rear derailleur (you may have developed a lot of play in it, and it is significantly cheaper than a shifter) and then look into replacing the shifters.

IIRC, the Shimano 105 shifters from about 10 years ago were shoddily built, so it may be the shifters after all.

  • It's definitely not the derailleur or any other component - I can reproduce the problem by disconnecting the cable from the derailleur and pulling on it by hand. – dpassage Nov 6 '14 at 21:55
  • Same can occur when the hanger is bent a little. – Alexander Dec 7 '14 at 4:39
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It could be the same stickiness problem but affecting a different pawl in the shifter? Try flushing the shifter with some sort of light oil; I use 3in1 oil with PTFE that can be bought from any auto-parts store for cheap. It comes in an aerosol can with a little red straw that should allow you to spray directly into the hole where the shift cable threads thru. Flood the shifter with the stuff to where it's dripping down the lever then shift thru the gears several dozen times and see if that helps.

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I wouldn't assume anything is bent or broken until you've gone through basic adjustments. It sounds like you just need more cable tension. While off the bike, upshift (inner lever on STIs) all the way out. Test by lifting up on the cable going to the rear derailleur. If there is slack, it is too loose. Loosen the bolt holding the cable to the derailleur and pull until there is no slack and re-tighten. Adjust further via adjustment knob on the derailleur.

Hope this isn't too elementary. This is one of those things that is so basic, I've overlooked it many times.

Cheers and good luck.

  • I've adjusted this seven ways to Sunday. At this point, one click of the inner lever results in the chain jumping from the largest cog to the middle cog, 5 full gears. If it was one extra or so, I'd believe you, but this is ridiculous. – dpassage Nov 6 '14 at 21:35
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    If it's jumping multiple gears every time, it sounds like something's broken in the shifter so gears are being missed when you shift up. – Holloway Dec 4 '14 at 11:12

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