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I just installed a new Alivio M4000 rear derailleur to replace a Tiagra derailleur on 1X-converted road bike. It looks wildly misaligned to me and shifts terribly.

The hanger is perfectly aligned. The first link of the derailleur seems aligned, but the second link doesn't, and cage seems skewed even further.

RDRDRDRD

Does this look defective? Or have I installed it poorly?

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    Was there much resistance when you were screwing it in? It is not too difficult to cross-thread it when you are first putting it in.
    – Kris
    Apr 19, 2018 at 1:26
  • No cross-threading, it mounts and unmounts easily. The mount is flush with the hanger.
    – Alex
    Apr 19, 2018 at 1:28
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    Something looks bent.
    – Daniel R Hicks
    Apr 19, 2018 at 2:40
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    If the hanger is straight, then I think your derailleur is bent somewhere - its very hard to know from pictures cos of distortions.
    – Criggie ♦
    Apr 19, 2018 at 2:45
  • It looks cross threaded to me. The entire body of the derailleur appears rotated in relation to the bike. If it was bent the upper portion should appear aligned. Also, the M4000 is a MTB derailleur. What shifters are you using? If they are not compatible cable pull ratios, etc... then you may have shifting issues unrelated to the alignment of the derailleur.
    – zenbike
    Apr 21, 2018 at 14:16

4 Answers 4

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Definitely something very wrong there.

The derailleur cage appears twisted around a vertical axis (the 'front' of the cage seems to be pointing outwards). A bent derailleur hanger typically rotates the cage around a horizontal axis (kicks the lower jockey wheel inwards). That makes me think the derailleur is bent rather than the derailleur hanger.

Do you have the old derailleur? Install that and see if the cage is parallel with the chainrings by looking down he chain-stay as in your first picture. If the old derailleur cage is parallel, the new derailleur is damaged.

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  • The old derailleur was aligned perfectly. A good portion of the misalignment on the new one seems to be coming from the second link connection (it's a direct-mount derailleur that came stock with Shimano's hanger adapter), but there's nothing obviously wrong with it or anything to adjust. I thought perhaps there was some configuration of this piece required. I think you're right though, I've started an RMA.
    – Alex
    Apr 19, 2018 at 18:10
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The derailleur itself appears to be bent (in fact, twisted). Since you say it's new, I suggest you return it for a refund or replacement. Perhaps it was damaged in shipping or perhaps it was defective from day one.

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A derailleur hanger tool is really the only way to tell if the hanger is bent. They’re fairly inexpensive and easy to use.

Or your local shop or coop might have one. It’s a very quick check.

If your hanger is straight but your derailleur is still bent then the derailleur is bent. You can try to bend it back into shape but it may not work properly.

I’d start shopping for a new rear derailleur and/or ask the place you bought this one to do a warranty replacement.

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    As in the post, the hanger is aligned. I have that tool.
    – Alex
    Apr 19, 2018 at 5:34
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Crashes can bend parallelograms and cages, pivots and bolts. As you likely well know. A cage with a bend in it, off the shelf, seems like a shipping mishap. Compare what you've been sold to a couple of others at your dealer's. Have them see reason, especially if your new one doesn't have scratches.

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