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Thread: Chump stumper - rear derailleur

  1. #1
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    Default Chump stumper - rear derailleur

    Apologies that this is kinda long and involved; feel free to ignore if not your thing.

    History:

    1) Stupidly stated that 9-speed bike never needed adjusting.
    2) Replaced OE rear derailleur with Sora. Worked okay ~1 year.
    3) Installed replacement chain and cassette (SRAM 971, 11/28).
    4) Broke chain on first ride. Lots of noise and a wreck; perhaps bent derailleur?
    5) Bike shop replaced chain with random, unwrapped chain pulled out of the bin, assuring me it was a SRAM 951.
    6) Installed replacement chain. Bike skipped in larger 3 or 4 cogs, no matter how adjusted. Sometimes it wanted to shift on its own, and sometimes it just jumped while staying on cog.
    7) Discovered that random, out-of-bin chain had a sticky link. Thanks, LBS!
    8) Purchased new SRAM 971 chain in actual original packaging Ö at a different shop.
    9) No longer jumps, but still tries to shift or skip in larger cogs. Sora derailleur appears to have a lot of play in it--much more than Ultegra on other bike, but not sure what's normal for Sora.
    10) Installed 10-speed Tiagra derailleur that was a spare to another bike. Shifts beautifully, except...
    11) I can get it to shift up to the largest cog (28), or the smallest cog (11), but not both. Limits from limiting screws are fine--the derailleur can move to all positions, it just doesn't want to stay on the largest cog unless I adjust it so much that it won't go to the smallest.

    Opted for the smallest cog since this is a triple and I can go to the small ring if needed. Barring other ideas, next step is to eventually take to shop to see if mount on frame is bent (no derailleur hanger). Mount could have been bent in wreck, and it maybe does look possibly a little wonky.

    Or I could just ride it since itís now shifting like an (8-speed) dream.

  2. #2
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    Could it be a shifter/rear derailleur compatibility issue?

  3. Likes Crickey7 liked this post
  4. #3
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    Quote Originally Posted by EasyRider View Post
    Could it be a shifter/rear derailleur compatibility issue?
    It could be, though I would expect that if I were trying to use a 9-speed derailleur for a 10-speed setup instead of vice versa, plus it shifts so well in every other regard. This was a consideration before I threw this on there, and I read conflicting advice on forums about whether it would work due to spacing, but it does seem to shift well so I think the spacing issue isn't one. It's just hard to find non-Sora 9-speed derailleurs nowadays so I thought I'd try this. I'm certainly amenable to picking up a 9-speed if I can find something better than Sora.

  5. #4
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    5) I've never seen a SRAM chain not say what model they are on each outer plate (like this). Maybe they exist, but I've ne'er seen it.

    I'm a mtb guy, so take this with a grain of salt, but I thought that 10-speed Dynasys used a different pull.

    https://www.bikerumor.com/2011/10/19...peed-shifters/
    "JOE @ SHIMANO: Not really. Anything with Mega9 on it was designed to work together as a 9-speed system, and anything with DynaSys on it is 10-speed only. The cable pull ratio is different. The 10-speed stuff pulls a lot more cable, and the lever arm on the rear derailleur is much longer. We designed it this way so when you do your shifts from the smallest cog all the way up, the lever feel is the same all the way through the range. Also, the 9-speed was more of a universal system, too, but the DynaSys is an exclusive mountain bike system."

    http://www.sheldonbrown.com/speeds.html
    "Shimano "Dyna-Sys" shifters and derailers use a longer cable pull than other Shimano models, and must be used together."

  6. #5
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    You matched cage length?

    In a totally unrelated bit of information, I have a brand new 10 speed Tiagra medium cage derailleur I'd let go for practically nothing.

  7. #6
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    What shifter are you using?

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    Quote Originally Posted by Crickey7 View Post
    You matched cage length?

    In a totally unrelated bit of information, I have a brand new 10 speed Tiagra medium cage derailleur I'd let go for practically nothing.
    I believe the cage length is supposed to be fine for this cassette--28 on large cog.

    If/when I replace, I'd like to do it with a 9 speed.

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    Quote Originally Posted by EasyRider View Post
    What shifter are you using?
    The 9-speed, I think it's Tiagra.

  10. #9
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    This smells like a slightly tweaked RDer hanger.

    Or, dirty/not-well-lubed cables and housing.

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  12. #10
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    Quote Originally Posted by Harry Meatmotor View Post
    This smells like a slightly tweaked RDer hanger.

    Or, dirty/not-well-lubed cables and housing.
    Thanks. Cable is new, so it's possible it's the hanger area/mount. Will take it in to have it looked at.

    Thanks to everyone for their ideas.

    ETA: (Poorly focused) pic of mounting area/RD:

    Click image for larger version. 

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    Last edited by huskerdont; 05-09-2017 at 09:36 AM.

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