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  1. #1
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    What makes this happine

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    I did a small drop about 2' and this happined... Bizzar! Never seen this before can't figure out why!?
    The most important thing is what God thinks about it. He will have the final say. Joshua Stinebrink

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  2. #2
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    Possibly your chain is too short and you cross chained big/big and it yanked the chain out of the rear der cage.

    Need more info. Full suspension?
    How did you size the chain?
    What length der cage?
    Triple crank?
    Look, whatever happens, don't fight the mountain.

  3. #3
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    Quote Originally Posted by savagemann
    Possibly your chain is too short and you cross chained big/big and it yanked the chain out of the rear der cage.

    Need more info. Full suspension?
    How did you size the chain?
    What length der cage?
    Triple crank?
    ok cannondale prophet, sized big to big + two links, short cage x9, double crank 36-22 slx
    I assume that I have every thing right..... At the moment I was in big-ring small cog....
    The most important thing is what God thinks about it. He will have the final say. Joshua Stinebrink

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  4. #4
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    The picture isn't great, but it looks like the halves of the derailleur separated. If that's the case it was probably caused by a loose bolt on the jockey wheels: have you played around with them recently?

    Tim

  5. #5
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    Nope the rear duerilluer is quite new and I checked the jockey wheel bolt and it was factory tight.
    The most important thing is what God thinks about it. He will have the final say. Joshua Stinebrink

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  6. #6
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    Weird.
    The only other time I saw this was someone had a road bike with Dura Ace 7900, upgraded the cassette from 12-23 to a 12-28 without changing the chain. Needless to say the chain was too short. He shifted into big big and the chain did that exact same thing.

    You said it is a short cage? Not a medium?
    Did you size the chain with the suspension compressed?
    If not, then there is a good chance that when you compress the suspension the chain growth could pull the chain out of the back of the derailluer.

    The Prophet is a high single pivot design. If I remember correctly, when I installed the chain on my buddies prophet, we needed a bit more chain length due to chain growth when the suspension is compressed.

    Having the short cage with a 36t chainring, combined with the fact that the suspension design is more prone to chain growth, you may need to go with a medium cage derailleur....or a smaller front ring.
    Either way, I'd start with a longer chain and take it from there.
    Look, whatever happens, don't fight the mountain.

  7. #7
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    I had to compensate for chain growth and gave it an extra link or two when I sized the chain I had to do it after I initially set it up. It took me a while to get it correct ( b screw ect) I'll try the drop again and see what happens I might need another link in the chain!
    The most important thing is what God thinks about it. He will have the final say. Joshua Stinebrink

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  8. #8
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    FWIW , add another link before anymore drops , less damage .

  9. #9
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    Certainly double check your chain length, and make sure it's correct throughout the swing arm's travel range. Often a chain that seems OK might be too short when the swing arm is flexed all the way.

    It would help if you remembered which gear you were in and whether pedaling or coasting through the drop, If in a mid to larger gear and pedaling at the time it might have been a "B" screw adjustment.

    Check the jockey wheel position on all the mid and larger sprockets and all the chainrings you use with them. There should be one to two links of free chain between the jockey wheel and the sprocket. If not, the jockey wheel can engage the sprocket through the chain, and snag pushing the RD back with goodly force.
    fb
    www.chain-L.com

    The key to solving any problem is to understand and address the underlying cause.

  10. #10
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    Need a medium cage unless 1x9 with a road cassette.

  11. #11
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    SRAM's
    "2008 NEW TECH. SPECIFICATIONS, ROAD / MTB COMPONENTS"

    gives the Short X0 a total capacity of 30 T. That is plenty for 1x9 with MTB casette. Just need the right amount of chain.

    http://www.sram.com/_media/pdf/sram/..._MY08_RevA.pdf

    (no Shorts listed in that document, at other levels)

  12. #12
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    The original poster runs a 36/22 on the front, so that is 14. 12-32 uses up 20, so that is 34. Chain stay growth during suspension actuation might be worth 1-2-3 teeth. so that is 35-37.

    Even with a single ring and 12-34 that is 22. With chain stay growth you're at 25.

    If you want stuff to work all the time, it is better to stay away from the edges of the envelope - especially if the suspension is active.

    Most folks not on a triple would be best served with a medium cage.

  13. #13
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    Seems really obvious to me that you mis-routed the chain through the deraillleur cage (although that picture is SO bad, that it is hard to see anything more than it is a rear wheel).

    If you pulled the chain hard enough to pull it out of the cage (you would actually have to pull the chain back and out to the side for this to happen), the cage would be bent badly, and either the B nuckle would break, or the hanger would be BADLY twisted. I short-chained a similar set-up when I first switched to SRAM (they lack the forward B-nuckle movement of the Shimano) and went thourgh a G-out in ~big/big and the result was VERY different that what (I think) is shown.



    2 X 9 with a short cage (on a FS) is just tempting fate.

  14. #14
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    +1 to what Dave said....looks like you mis-routed the chain through the der on install.

  15. #15
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    Quote Originally Posted by apat13
    +1 to what Dave said....looks like you mis-routed the chain through the der on install.
    Agreed.
    Oh noes. I'm going to drink the Kool-Aid.

  16. #16
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    looks fine to me - that's how I route mine all the time.
    Honestly... ahh I give up

  17. #17
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    Quote Originally Posted by highdelll
    looks fine to me - that's how I route mine all the time.
    Unless the der plates separated on the landing (and OP has already said the bolts were/are tight - that is they did not separate) there is no way the chain could end up on the outside of the cage like that unless it was originally, accidentally routed outside the little tab on the bottom of the plates/cage.

  18. #18
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    Were you guys being funny about me routing the chain wrong..... ?
    For what's it worth I stated I was running in the 36 chainring up front and small cog in the back when I did the drop as I stated before if you read my post #2 I gave the bike an extra 2 links + 2 extra to compensate for chain growth. I'll add a few more links than try the drop again later.
    The most important thing is what God thinks about it. He will have the final say. Joshua Stinebrink

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  19. #19
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    I thought the chain was routed incorrecly too. I didn't want to post because I was giving you the benefit of the doubt, maybe the picture was tricking me. Don't want to imply you routed the chain wrong, but it's either that or you need to post a better pic.

  20. #20
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    If the lower pulley bolt is still intact and tight as you indicated, than the ONLY way a chain could end up where it is in your picture is if is was not correctly routed through the lower pulley when the der/chain was installed. Unless the pulley bolt magically broke, popped the chain out, then magically refixed itself on your landing....

  21. #21
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    The X0 cage is carbon, and can flex open enough to let the chain come out of the back if the derailluer is forced forward by a short chain or some other force.
    Like I said, I saw the exact same thing happen to a Dura Ace 7900 derailluer, which has a similar carbon cage as well.
    If this was an alluminum cage, I wouldn't see it flexing open like that without considerable damage to the cage, and or chain..
    Look, whatever happens, don't fight the mountain.

  22. #22
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    maybe you can post a picture of that der, because the only ones I've ever seen would be impossible for the chain to come out from the cage unless the pulley breaks.

  23. #23
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    Quote Originally Posted by savagemann
    The X0 cage is carbon, and can flex open enough to let the chain come out of the back if the derailluer is forced forward by a short chain or some other force.
    Like I said, I saw the exact same thing happen to a Dura Ace 7900 derailluer, which has a similar carbon cage as well.
    If this was an alluminum cage, I wouldn't see it flexing open like that without considerable damage to the cage, and or chain..
    How can any cage "flex open" with its lower pulley bolt still in place and tight? In order for the cage to "open" there has to be an opening. If there is no break in the cage, that opening can only be at one of the bolts. If the bolts are still intact/tight, then nothing opened - aka, the chain was not routed correctly which is why it is outside of the pulley.

  24. #24
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    Quote Originally Posted by apat13
    How can any cage "flex open" with its lower pulley bolt still in place and tight? In order for the cage to "open" there has to be an opening. If there is no break in the cage, that opening can only be at one of the bolts. If the bolts are still intact/tight, then nothing opened - aka, the chain was not routed correctly which is why it is outside of the pulley.
    cages are NOT one piece.
    Honestly... ahh I give up

  25. #25
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    Photobucket Pictures, Images and Photos

    Photobucket Pictures, Images and Photos

    here's a few pics as requested of the offending X9
    as you can see it's still in one piece and after I loosened the screw that holds the jockey wheel and re-routed the chain everything is alright!
    The most important thing is what God thinks about it. He will have the final say. Joshua Stinebrink

    ____
    Kimo

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