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First time posting, hope I can get some suggestions on this weird issue I've noticed with my shifting. I have a fairly decent understanding of how to maintain gears myself, and have made quite a few attempts at trouble shooting this, so unless I've missed something it seems to be something beyond the obvious 'reindex, replace cable-housing, lube chain' sort of thing.

The Problem
So basically, my 9-speed shifters which are a few years old, seem to only click through 8 speeds, both ways. This manifests in the chain always 'skipping' a cog on the 9-speed cassette no matter how I index, although I think the cog it skips varies depending on whether I'm shifting up or down.

Notes

  • I have recently replaced the chain, the cassette, the cables (lubed) AND the housing, so I am fairly certain it is none of these.
  • The deraileur seems to be indexed correctly: transmission is quick and crisp and and both extermes of the cassette can be reached when shifting through all the speeds.
  • I have come off the bike on the the derailleur side before, but the fact both extremes can be reached seems to suggest a bent mount isn't the problem?
  • The shifter seems to physically only click through 8 speeds, despite most definitely being 9 speed.
  • Chain is 9 speed

For all I know it could be a common problem, but not one I'm familiar with. Is there some sort of adjustment needed on the shifters themselves?

Any informed suggestions greatly appearciated!

Thanks

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  • sorry, can you clarify? You have a 9sp cassette and when you use the shifters you can go from one extreme to the other, but somewhere in the middle you're skipping one of the sprockets? Is that what you're saying? – PeteH Dec 24 '14 at 10:04
  • Hi Pete. Yes that's exactly it. 9sp casette and shifters, but no matter what I do, there is always a sprocket that will be skipped (usually in the middle), and the shifters will only 'click' 8 times from one extreme to the other. For a given cable tension, the cog that is skipped will be consistent every time I shift in that direction, although I can usually get onto that cog if I shift back the other way. – Peppers16 Dec 24 '14 at 10:09
  • Hmmm....not obvious. I mean, you can check the shifter standalone, just disconnect the cable from the derailleur and you should be able to feel the shifter pull/release through 9 clicks. Best guess so far would be a bent derailleur, but that doesn't necessarily tally with everything you've said. I'm thinking if maybe the limit screws, which sound like they are positioned correctly, are preventing the shifter from reaching the ninth (or the first) gear (as far as the shifter is concerned). – PeteH Dec 24 '14 at 10:49
  • I think shifting without cable tension might be a good shout, diagnosis-wise. I'm sure there was one time where I found I could just reach one more speed at the largest-sporcket if I applied a lot of force to the shifter (as if the cable tension against the limit was preventing the final speed). It'd be consistent with the bent hook theory, but still a bit weird that I can reach both extremes without problem. In that case I'd expect the chain to stop short of the smallest sprocket. – Peppers16 Dec 24 '14 at 11:35
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    Are you sure it's missing a gear? Have you actually watched the chain skip over a cog? As @kibbee points out in his answer, a 9 speed setup should only click 8 times from one extreme to the other. – jimchristie♦ Dec 24 '14 at 16:48
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I'm kind of confused here. You say you can only click 8 times. On a 9 speed bike, there would only be 8 clicks for shifting. Let's say you start on the largest gear, and we'll call that 1. Clicking 1 time with bring you to gear 2. Clicking 2 times will bring you to 3. Clicking 3 times with bring you to 4. Continuing on with the pattern will bring you on to clicking 8 times to bring you to 9.

If you bike was skipping a gear somewhere in the middle, you would shift 7 times, and already be on the smallest gear, and shifting one more time would bring you nowhere, as you would already be at the bottom. The limit screw would keep it in it's place, and the cable would go a bit slack. Going up the cassette you would notice a problem where you still had 1 click left, but would be unable to move the shifter because you would be pushing against the limit screw.

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  • yeah you're absolutely right, my comment above should have read 8 clicks (for his 9sp shifter) – PeteH Dec 24 '14 at 15:33
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A bent derailleur can still be a problem even if you can reach the extremes of the cassette -- since you said you don't think it is a problem, it sounds like you haven't actually checked it, so check it. Park Tool has an excellent page on checking derailleur adjustment.

You also said you replaced the cables + housing -- if these have been routed improperly, this can also affect shifting. Also, modern cables are not recommended to be lubed by their manufacturers.

As PeteH said in the comments, try clicking the shifters to see if you can shift through the entire range without cable tension. Shifters do wear out over time and sometimes don't catch on the shifting pawls if they have worn out. If the shifter is indeed not hitting all the gears, I'd probably just live with it -- some people have some luck blasting the shifter with WD-40 if its just gumming preventing the thing from catching but taking apart a brifter, repairing it and putting it back together again is a non-trivial task.

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Thanks for the answers, guys. For the benefit of anyone who's come across this with the same issue:

As you both suggested, a bent derailleur hanger was indeed the problem, and bending it back out with a spanner and re-indexing resolved the issue (although shifting isn't quite perfect).

I falsely assumed, with my limited experience, that this problem would have prevented extremes of the cassette being reached. What actually happened is the bent angle caused the outermost 'speed' to point out, beyond the range of the cassette and into an area prohibited by the limit screws (as diagnosed by several answers), giving the impression (with cable tension applied) that the shifter couldn't physically acheive this final speed. I (unknowingly) compensated for this by setting an eccentric range with a lot of movement towards the large sprocket, and a severe limit at the small sprocket (this was evident just by looking at the screws). So both extremes could be reached despite the bend.

So yes, bent derailleur was the issue and I know the suspect this straight away in future :)

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