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  1. #1
    bjk
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    New question here. 575 chain kicking

    While cranking my 575 over very rocky, bumpy terrain, my chain will kick off my front chainring in a loud, violent "pop." It happens as the rear suspension is heavily compressed while pedaling. I think the rear cassette is forced to rotate forwards as the suspension compresses(this is good I think), which is causing chain tension/timing issues and making it kick off the front chainrings. It really is a hassle since I have to stop pedaling when it happens, and I loose all momentum up climbs and also flat rocky ground. Today the chain was on the middle front ring, and it completely kicked off and all the way to the inside of all the rings and onto the bottom bracket - this happened once. It violently popped about 5 other times today in 5 hours, which was frustrating. My 575 shifts really well btw. I'm sure that I should be able to crank while the suspension is really working over rough terrain. Anybody else have this issue? Maybe chain tension issues? The bike is about 2 weeks old now. Not sure what to do. BTW, the chain really seems to slap around with an extreme amount of noise on fast bumpy downhills - not sure if that's normal. Any pointers would be greatly appreciated!

    Enduro build, med
    XO rear, xt front, x9 shifters
    Last edited by bjk; 07-11-2006 at 10:56 PM.

  2. #2
    trail "cleaner"
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    few things to check

    1. chain length. while in middle chainring and large cog, where is the derailleur jockey positioned? Should be pointing between 4-6 o'clock. If jockey is positioned at say... 7-9 o'clock.. this is too loose and will result in the chain flying off.
    2. What gear are you using when the chain pops off?
    3. Many new outboard bearing cranks have horrible chainlines and are prone for this type of behavior. So... what crankset are you using?
    4. Lastly, buy one of these to prevent the chain from going all the way down to the bottom bracket. http://www.ronniering.com
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  3. #3
    bjk
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    Listen!

    1. chain length. while in middle chainring and large cog, where is the derailleur jockey positioned? Should be pointing between 4-6 o'clock. If jockey is positioned at say... 7-9 o'clock.. this is too loose and will result in the chain flying off.The whole derailleur is pointing at about 5 o'clock, so that sounds ok

    2. What gear are you using when the chain pops off? The middle chainring usually, sometimes the small one. Usually around the 3rd to 5th gear from the biggest in the rear. It usually doesn't come all the way off, but it is more like a loud, popping skip of the chain over the middle chainring.

    3. Many new outboard bearing cranks have horrible chainlines and are prone for this type of behavior. So... what crankset are you using? Raceface evolve, the one that comes with the enduro package. What do you mean by "chainline"? Thanks for the help! Bryan

  4. #4
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    Quote Originally Posted by bjk
    .........3. Many new outboard bearing cranks have horrible chainlines and are prone for this type of behavior. So... what crankset are you using? Raceface evolve, the one that comes with the enduro package. What do you mean by "chainline"? Thanks for the help! Bryan
    Chainline is the distance from the middle of the Bottom bracket shell to the middle chainring

    I'd be care with this if you are going to play with the chainline. Currently using RF Deus crank with a Hone front derailleur on a 575 carbon. I like to run a 49mm chainline so with X-type BBs i put the drive side spacer on the non-drive side. In this configuration the inside cage of the derailleur hits the swingarm. I am running a 51mm chainline now and the bottom of the derailleur only clears by .5mm and who knows may hit on a hard bottom out.

    Last weekend i was riding a techy trail with 2 others with X.O setups, I am running a 4 year old XTR rear derailleur (old and very used) on my Yeti and they were on a 5-spot and Flux. I didn't drop my chain once on the trail and they each dropped their chain 2 times.

  5. #5
    trail "cleaner"
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    a little more info..

    Quote Originally Posted by bjk

    2. What gear are you using when the chain pops off? The middle chainring usually, sometimes the small one. Usually around the 3rd to 5th gear from the biggest in the rear. It usually doesn't come all the way off, but it is more like a loud, popping skip of the chain over the middle chainring.
    OK a couple more things... how old is your Drivetrain? Could be a sign of a worn chainring. Also, have you recently changed out your chain?? A new chain on a worn drivetrain will cause this type of problem. I'm assuming that your shifting is "spot on" from one gear to the next.
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  6. #6
    bjk
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    Drivetrain is about 2 weeks old. I think it has more to do with the top side of the chain changing tension when the suspension flexes and I crank at the same time - and I have no idea what to do about it! I've had it happen and it's so loud that my group looks over and thinks I have broken something. I never change gears while cranking of course.

  7. #7
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    Would this rear deraileur work on the 575?

    http://www.blueskycycling.com/produc...-Combo-Kit.htm

  8. #8
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    ya thats what i run with an XT front der and it works flawlessly

  9. #9
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    Quote Originally Posted by Tejas Mtb
    ya thats what i run with an XT front der and it works flawlessly

    Not knowing a lot about the rear der. I wondered if there was a need for long cage or not.
    Thanks for the info.

  10. #10
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    i have the same problem on my 575, but just with the granny gear.
    my chain lengh is not the problem. i've sized the chain down so that the big big combo is really tight.
    today, i replaced my 22t ring with 24t to see if the larger ring would help. it did not.
    in the past couple of months i've swapped out to a 34t cassette, a new chain, new hanger last weekend, and new rings today.

  11. #11
    bjk
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    mappable, did those alterations fix the problem? Also, has anyone used a chainguide with a bashguard, like that e13 one? You can still shift between 2 chainrings in the front. Might be sweet on a 575.

  12. #12
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    has anyone actually installed the ronniering mentioned above on their 575?

    they have a picture of a ronniering below installed inside the grannygear on a 575

    my chain will drop to the bottom bracket on only the granny gear and the largest cog under heavy pedal pressure on steep ledges.

    i've had good luck running a bad chainline with my middle blackspire ring on the largest cog with out issue. i just don't have the legs or power for the hardest climbs. so i'm thinking maybe the ronniering might be the trick to allowing me to use the granny on the 575.


  13. #13
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    Yep!......

    Ronnie is one of my riding buddies and I have Ronnie rings on both of my 575's. Say goodbye to chains eating up your bottom bracket shell! I've been running them for two years and never had a chain fall off of the granny chainring.
    No dabs allowed!

  14. #14
    In my mind, I can do it!
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    I have the same bike, the enduro package, and have never experienced this. There may be something to riding style as well on this. I have a friend that has popped several chains and broken them. He is probably shifting under load or something but this has not happened to me and we ride the same trail.

    If you aren't shifting (and you are sure you aren't accidentally shifting. It happens to me when shifting from the large chainring to the middle that I double click the shifter and pop down to the small... It's easy to do) then it sounds like some adjustment is off. The chain has yet to pop off on mine though.

  15. #15
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    here's another option suggested to me

    has anyone used the n-gear jumpstop on their yeti?


  16. #16
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    Let me guess - XT cranks. Shimano chainrings are crap. Shimano admits it and has been providing LX replacements. I swapped mine for RaceFace chainrings (they fit the XT crank arms perfectly) and I've cured the exact same problem you describe. I've had that same problem on borrowed bikes and various demos all with XT cranks.

  17. #17
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    Before you go buying new stuff, make sure you've found the actual problem first. I'd bought a new chainring in response to my chain dropping from middle chainring under hard torgue (standing/pedaling hard up rocky steps). I'm riding an OEM 575 with truvativ cranks. Found that the non-driveside crank bolt was backing out 'just enough' to work fine under normal conditions but would almost always drop the chain under hard torque. My best guess was that my right leg was pushing the crank arm down thus forcing the driveside to move out just enough to cause chainline issue; I've since cleaned and lock-tited the offending bolt. Everything good now.

  18. #18
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    I was having the same problem and replaced my granny chainring and got a ronniering thingamajig also. Not shure which one made the difference but I haven't droped a chain since.

  19. #19
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    BJK....have you?

    Taken it back to the shop?
    My set up is an XT crank, XO rear D, XO twist, no problems at all. SRAM recommends that you run the chain around the big rings front and back...but NOT through the rear D...and you should have 2 links of overlap. Do you have significantly more than that?

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