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  1. #1
    LUW
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    Bonking ... not feelin' well 2011 X9 rear derailleur

    About two weeks ago on the half-way back home from a 40 km my chain went suddenly slack to the point it wrapped between the cogs and spokes . I was in a steep climb and going very slowly, and didn't have time to unclip, so I just braced myself and fell over like a sack of potatoes. I managed to unwrap the chain and at first thought that the rear derailleur got loose, so I tightened that screw that regulates the tension of the derailleur, hopped on the bike and continued home, but taking it easy.

    Since the bike is still under warranty, I took it to my LBS and there the mechanic told me that the internal derailleur spring got loose . On the first half of the ride I went through some hairy rocky downhill, with lots of teeth shattering vibration, so probably it happened there. He also said that I wouldn't be able to adequately fix the problem on the trail. And on the first half of the ride I was marveling at how smooth the X9 shifters/derailleurs were shifting...

    So, is this a common issue with a X9 ?
    Cheers!
    Luciano
    Brazil
    - 2011 Cannondale Flash Carbon 29er 3

  2. #2
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    Your mechanic has no idea what he is talking about. I guarantee that the low limit screw wasn't set properly at the shop and that is why your derailleur went into the spokes. It seems he might be covering his butt by making up the "internal spring tension got loose" thing.

  3. #3
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    Quote Originally Posted by fixbikeguy View Post
    Your mechanic has no idea what he is talking about. I guarantee that the low limit screw wasn't set properly at the shop and that is why your derailleur went into the spokes. It seems he might be covering his butt by making up the "internal spring tension got loose" thing.
    Or your hanger is bent, either way it sounds like an adjustment issue not a "loose spring"

  4. #4
    LUW
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    It wasn't the derailleur that went over the cogs into the spokes, but the chain. When I got off the bike and saw what happened, I thought that some how the chain got stretched out. The tension screw was screwed almost all the way out, and I remember thinking that it should have gotten loose somehow, so I tightened it almost all the way in (pulling the derailleur backwards and tensioning the chain) and was able to ride home. However, on the way back and afterwards even on smooth asphalt, if I pedaled hard in the highest gear, sometimes it seemed that the derailleur "jumped forward". That only happened under power and in the highest gear (3911), but on the stand, hand-cranking the pedals it was shifting smoothly.

    I got the bike back last week and after a whole week of miserable weather yesterday I finally was able to take her for a spin. I did some 17 km really hammering the pedals and it's working perfectly smooth again, in all conditions. They set the tension screw out how it originally was, and on the day I took the bike in there was a brand new Flash 3 26er there and the tension screw was also out like mine was and is now. That's why I didn't second guess what the mechanic said.
    Cheers!
    Luciano
    Brazil
    - 2011 Cannondale Flash Carbon 29er 3

  5. #5
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    All that the tension screw does is set the distance between the top pulley and the cassette cogs. It does put a bit of extra tension on the chain, but it is there to set the gap so the shifting is better. The lower limit screw is what controls how far the derailleur goes to the wheel. If the lower limit screw was set properly and the hanger was not bent it is virtually impossible for the chain to go past the cog and into the wheel. This is why I believe that the chain did that. The mechanic was correct in saying that the spring tension screw needed to be adjusted as you adjusted it yourself incorrectly, but this was not the cause of the original problem.

  6. #6
    LUW
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    But what would make the chain become so slack? It was visibly sagging.
    Cheers!
    Luciano
    Brazil
    - 2011 Cannondale Flash Carbon 29er 3

  7. #7
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    What might have happened is that the spring that keeps tension to the cage part of the derailleur could have become dislodged. Its an uncommon occurrence as the internal parts of the derailleur generally don't have the chance to move, and on a newer derailleur there is generally not enough wear to cause those parts to have any slack.

    The b-screw works on the main derailleur spring which is wrapped around the mounting bolt. This would have had no effect if what I postulated occurred.

    Hope the bike/hanger/you are all ok. The last time I did a horizontal trackstand I impaled myself on a stump.
    Rimmer - "There's an old human saying - if you talk garbage, expect pain"

  8. #8
    LUW
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    Alex, what you say is inline with what the mechanic told me, and from the way the chain got loose I would say it seems a very probable explanation.

    I had the good grace to lie down on my left side, so except for some very minor bruises and scuffs nothing else happened.
    Cheers!
    Luciano
    Brazil
    - 2011 Cannondale Flash Carbon 29er 3

  9. #9
    LUW
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    No good

    And it wasn't an isolated incident...

    It happened 2 more times, the last one about two weeks ago. I had enough so I demanded a new RD, and under warranty got a brand new X9. But now with the new RD, if I'm pedaling through bumps, sometimes the derailleur "ghost shifts" - like it starts to shift but then the chain falls back on the original sprocket again. That never happened with my original RD, and it's not really a problem, but it is annoying.

    So I gave up and ordered a XO unit. Honestly, in the beginning I was raving about SRAM parts, but now I feel that my initial gut feeling was right: I should have gone with a XT group. Over two decades using Shimano parts and never (EVER!) had any issues like this .
    Cheers!
    Luciano
    Brazil
    - 2011 Cannondale Flash Carbon 29er 3

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