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SRAM XO / chain issues jumping chain suck

jfk262jfk262 Posts: 13
edited June 2012 in MTB workshop & tech
Problem:
My chain keeps jumping & mischanging with rear gear changes and chainsucking with front gear changes

What have I got?
Bike: Trek Fuel EX9 2010
Rear Mech: SRAM XO
Front mech and chainset XT 9 speed
Chain SRAM PC 971

History
Perfect all time best shifting for several months from new
Removed rear mech, chain and chainset to return bike to Trek for warranty issue (seatpost)
Re built bike and chain issues started
May have changed chain at he same time or after problems started. Can’t remember. Previous perfect shifting chain was orange Taiwan one from Merlin

What have I done?
New rear gear cable (XTR): no change
Re set rear mech according to SRAM manual for jockey wheel distances & screw tension etc: tiny bit better
Cleaned, lubed and greased inc jockey wheels: tiny bit better
Checked chain: not worn

I seem to have narrowed it down to the chain or rear mech as when I rear pedal on the middle gears of the cassette the jockey wheel arm moves forward occasionally as if under tension. Looked for stiff links: none. You can see video here: http://youtu.be/_Pm-zzetkew

Bottom jockey wheel slightly worn but not star point level. Never had this issue before on many rear mechs even with well worn ones.

Any ideas? Seen this before? Rubbish chain?
It’s driving me mad! Or can you recommend a talented mechanic in the Leeds area.
Cheers
Joe

Posts

  • nicklousenicklouse Posts: 50,675 Lives Here
    To me that is a stiff link or a hub issue.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • jfk262jfk262 Posts: 13
    nicklouse: interesting you should say hub as I forgot to add that my rear hub (Bontrager, DT SWiss in disguise) got full of water on the first wet ride I did and I re built it. I think I put too much grease on the delicate pawls (only 2 springs) and occasionally there's a 'crack' of them jumping into place. Was thinking of getting new rear as I put a flat spot in too and not inmpressed by the inetrnals of the Bontrager/ DT Swiss
  • jfk262jfk262 Posts: 13
    So, re bult and re greased rear hub from manual. Crack nosies gone (well up and down the road a few times anyway) but, you guessed it, still does jockey arm moving forward thing.
    Any more ideas anyone??
  • jfk262jfk262 Posts: 13
    But now it only does it on the 4th largest cog/ ring down on the rear cassette.
    When I put it on the front big ring and back pedal it gord crazy and drops down 3 rear cogs/ rings. wtf?
    Mech doesn't move the chain just jumps down????
    Chain line issue?
    Have re tensioned rear gear cable to ensure it's set properly.
  • nicklousenicklouse Posts: 50,675 Lives Here
    With out seeing it it is hard to say.

    May thoughts are some thing is bent or sorry set up/fitted incorrectly.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • pilchpilch Posts: 1,136
    jfk262 wrote:
    Removed rear mech, chain and chainset

    Did you put the spacers back in the same place(s)?

    Is the mech hanger bent?

    Is your cable routing good?
    A berm? were you expecting one?

    29er race

    29er bouncer
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