Viewing 11 posts - 1 through 11 (of 11 total)
  • Help – SRAM X9 Rear Derailleur Problem
  • spiddy
    Free Member

    Hey all,

    Hoping some STW gurus may help me out with this one.

    I caught my chain on a branch during a ride at the weekend, it stopped me dead and bent my rear derailleur hanger. A quick bodge fix on the trail got me home with some awkward shifts.

    I got home and straightened the rear hanger – so far so good. However when checking the shifts I noticed my granny ring is now pretty useless as chain slack on all but the biggest cogs is horrendous!

    Pic below shows slack on small-small combo:

    To troubleshoot I checked the following:
    1) Check rear derailleur for damage – nothing snapped, bent or out of shape
    2) Removed and refitted derailleur – no probs
    3) Checked H, L and B-tension adjustments – all good
    4) Checked chain wear (I’m grasping at straws now) – fine
    5) Checked frame, dropouts and BB for damage – fine

    Edit: There is a small screw on the pivot barrel I left untouched. Could this be the one? (might try this one tomorrow)

    Other than granny ring slack it’s shifting as good as always. In short I’m stumped, anyone have ideas how to fix?

    NorthCountryBoy
    Free Member

    What does the chain tension look like when in middle ring front and middle gear on the cassette? Grany ring / small gear is a pretty odd combo, maybe it was always that slack but you never used that gearing?
    The mech looks in the pic likes its pulling back as normal there is just too much slack to loose. So assuming in the crash no one added 6 extra links to your chain…. perhaps its not so bad.

    spiddy
    Free Member

    Thanks NCB. On middle-middle it looks fine (I’ll take another pic tomorrow), chain under tension as expected – maybe a little “bouncy”.

    I double checked the chain length too and it’s setup with the recommended one link overlap on big-big combo. It may well be I just haven’t noticed until now as I tend to stick with middle or outer front rings.

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    TooTall
    Free Member

    Damaged the springs that give the tension? Something blocking the movement of the springs?

    spiddy
    Free Member

    TooTall the springs all look flush and the RD is functioning properly.

    NorthCountryBoy I think you’re right. Following hours of derailleur tweaking and web searching I’ve came to the conclusion that this is how the X9 is meant to be – not that I’m happy about it as compared with a Shimano derailleur (on my other bike) the slack on the X9 in small-small is bad!

    I found this quote on another thread:

    On the ’10s SRAM is overstating the capacity by at least four teeth (as per their instructions, and dependent somewhat on CS length. 45t for a long cage, ie a standard MTB 22-32-44/11-34 setup). This issue was actually brought to my attention by John Barnett (of BBI) and after checking dozens of bikes can thoroughly confirm his findings. The problem seems to stem from the DiRT cable routing they used on the ’10 X9 and X7 derailers, which has been changed for 2011. If you install the derailer per SRAM’s 6mm gap spec and size the chain to their method you will usually find that the chain will hang slack in small/small (a potentially dangerous situation). And if you size the chain with Barnett’s method you will find you can’t make the shift to big/big, both indicating failure of capacity tests.

    Now most mechanics will just leave the chain long and crank down the B (which SRAM and Barnett will tell you will adversely effect shifting to some extent), or assume that people wont use a gear they are not supposed to (yeah right). Hell even SRAM will tell you to leave the chain slack, which again can be dangerous and they don’t seem to care about.

    There’s not much more I can do other than try to avoid the slack combos altogether.

    Northwind
    Full Member

    None of mine do that. Can’t tell from the pic, is that a medium cage?

    oliverd1981
    Free Member

    so just run it short? What possible use is big-big?

    Corect chain length = as short as you can get away with.

    What’s tight is light.

    I have a 4spd X9 mech somewhere in the garage.

    TheSwede
    Free Member

    Stop in the correct position? The one that spins on the main bolt. Can get knocked past the hanger in a smash and then the mech wont tension properly.

    nosedive
    Free Member

    interesting

    i wouldn’t shorten the chain though, i ran one a couple of links short with a brand new x7 mech. lent it to a mate who bottomed out the suspension and the chain growth ripped the mech to pieces (not sure if your suspension design would do the same thing though?)

    tbh looks like a replacement mech job to me, even if it doesn’t solve the problem you can always use another mech in future. x7 mech £35 from merlin

    spiddy
    Free Member

    @Northwind: Sorry bad pic, it’s a long cage. Pretty sure slack wasn’t this bad before the incident.
    @Oliverd: I’d prefer to keep chain at correct length and be more disciplined with my shifts.

    @TheSwede
    : I know the piece you mean, I’ll double check this tomorrow. If the RD was a quarter turn tighter this would fix the problem.

    Thanks for your help folks! Much appreciated.

    doug_basqueMTB.com
    Full Member

    Spiddy, I had a problem with my X9 last week. 10 speed if it makes a difference. Basically it must have had a knock and the spring that tensions the lowest jockey wheel was damaged. There was still some spring tension in there but it would only let me ride when I used bigger cog combinations. I screwed the q-screw (is that what it’s called?) all the way in to try and tension it more but it didn’t help much.

    It looked exactly like yours I think. Looking at yours the bottom jockey wheel isn’t pulled all the way back up is it?

    I’m rushing to eat and get out guiding so sorry if I’m not being very clear. Basically the solution for me was to buy a new one… i have the old one and when I get a spare hour I’ll investigate to see what went wrong.

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