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I have a Boardman CX Team 2014 with some indexing issues. It's running a Shimano Sora ST-3500 9 speed shifter with a Shimano Sora rear mech.

The gears had not been running all that smoothly and, as I was changing the bars, I figured I'd also re-cable everthing with new housing. The gears are now shifting a lot better, but there is a small problem with the indexing on the rear derailleur.

When fine turing with the barrel adjuster I can get wonderfully smooth shifting on the smallest 4-5 cogs, but after that it gets a little less smooth.

Can anyone give me some pointers on what to check to get it working smoothly?

EDIT:

Photo showing cable connected to rear mech

enter image description here

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    Just a hunch, but could you add a photo that shows how the cable is connected to the derailleur? – ojs Aug 22 '19 at 8:21
  • @ojs How's that? – ben_re Aug 22 '19 at 8:50
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    Did you change anything else on the bike? And you might want to try screwing the "B" screw in some - that's the topmost of the three screws in your picture. It's also not screwed very far at all... Screwing the "B" screw in will move the derailleur further from the gears, and since your problems only happen on the larger gears, that seems like it might be related to your bad shifting. It's also really easy to do and undo. – Andrew Henle Aug 22 '19 at 9:59
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    @ben_re that looks correct, so it must be something else. To me it looks like the pulley is really close to cogs, so I agree about the B-tension screw – ojs Aug 22 '19 at 10:04
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    If the B screw doesn't help, the symptoms could indicate a slightly bent derailleur hanger, fixed link this: bicycles.stackexchange.com/questions/3666/… – StefanS Aug 22 '19 at 12:04
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B-tension issues rarely pop up spontaneously. Once it's set, you usually don't have to ever touch it unless you change to a much larger or smaller cassette. Unless you messed with it already...

I see the scrapes on the derailler and think your DR hanger is probably bent. This can cause irregular shifting issues like you mentioned-- good in the lows but bad in the highs, or vice versa.

Or, your cassette/ chain might be worn out. Do you usually ride in the big cogs? If so, those will be the first to wear out and they might not shift right, while the unworn smaller cogs still have the sharp ramps to shift well.

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    The visible teeth on the cassette look to be in reasonably good shape, actually. – DavidW Aug 22 '19 at 20:44
  • It's increasingly sounding like a hanger issue. I can get smooth shifting in the lows OR the highs, but not both. I'll get a replacement and let you know if it solves the problem. – ben_re Aug 23 '19 at 8:00

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