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  1. #1
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    Please Help Me Save My Nuts!

    I need help from the collective in troubleshooting a problem with my (4-bar link) 5-Spot.

    Background
    Built up myself 3 years ago. Drive train:

    New XT external BB crankset
    Shimano chain ring
    Shimano front DR
    SRAM XO grip shift
    SRAM chain
    XT cassette
    XO rear DR

    Rode the hell out of the bike and it treated me like a king on the singletrack.

    Problem
    New job. More money than time. Took the bike to my LBS and spent several hundred $ to replace with the same set up listed above:

    small and Middle chainrings (shimano)
    chain
    cassette
    rear triangle bushings (ordered from Turner)

    So when I'm on the singletrack and torquing hard, the chain pops off the middle ring to the lower ring. Not when I'm spinning, but when I'm mashing. Like torquing to pedal kick off a drop, or standing up and leaning forward to j-hop up on to a rock at the top of a climb.

    The chain pops off the middle ring and down to the small ring violently. And I have bruises from my knees to my nether regions from hitting the stem/steerer tube.

    Front DR is set correctly.
    I *think* the spacers for the XT crankset is set correctly (a spacer on the non-drive side)
    I wound up snapping the (new) chain so that's replaced.
    Chainring bolts are tight

    Anyone have this problem? Any thoughts? my knees and nuts will thank you.

    Ken

  2. #2
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    Reputation: jokermtb's Avatar
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    I suspect it's the middle ring......sometimes a bike shop will slap a cheapass LX middle ring on [since you can't really tell if it's an LX or XT!] and they are very bendy and the teeth suck. Try replacing it with a thicker Race Face middle ring and see what happens.....I know it's silly to ask, but could they have put on the middle ring backwards, w/ the grabbers facing the big ring?

    New, or even old worn out bushings will not cause this to occur.

    Also, check to see if the cassette lockring is tight. Lastly, if you have king hubs you may need "the spacer"

    Your bike should not be skipping w/ a new middle ring - replace it and go buy a mini-van to place your nuts in it's dashboard mounted mason jar for safe keeping.
    Yes, we do indeed rock...http://www.myspace.com/spokedrunkies

  3. #3
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    Did you check the cable tension? First place I look when having shifting problems.

  4. #4
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    XT ring...

    Quote Originally Posted by jokermtb
    I suspect it's the middle ring......sometimes a bike shop will slap a cheapass LX middle ring on [since you can't really tell if it's an LX or XT!] and they are very bendy and the teeth suck. Try replacing it with a thicker Race Face middle ring and see what happens.....I know it's silly to ask, but could they have put on the middle ring backwards, w/ the grabbers facing the big ring?

    New, or even old worn out bushings will not cause this to occur.

    Also, check to see if the cassette lockring is tight. Lastly, if you have king hubs you may need "the spacer"

    Your bike should not be skipping w/ a new middle ring - replace it and go buy a mini-van to place your nuts in it's dashboard mounted mason jar for safe keeping.
    It's an XT ring. Brand spanking new. On correctly with the shift ramps (grabbers?) facing toward the non-drive side of the bike. I thought of that too and it was one of the 1st things I checked. I've been running the same basic combination in the drive train since a little after 8-speed cassettes first came out. I'm unlikely to jump ship to RF even though they make fine products.

    Cassette lockring is tight. I'm running a Mavic XL wheelset.
    Last edited by Ken in KC; 06-01-2006 at 08:16 PM.

  5. #5
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    Quote Originally Posted by Suicider
    Did you check the cable tension? First place I look when having shifting problems.
    The cable tension of the front DR? Yes. The tension is fine. Since this has been happening, I've been using the front DR as a chainguide and favoring closer to the big ring vs. right in the middle.

  6. #6
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    I know it's a longshot, but could the quick link on your sram chain be oriented so that under stress, it may be catching on one of your shimano chainring guide pins, or catching on some part on your front DR [if it's off axis a little].....or a sticky chain link that isn't bending quite right....check each link for ease of movement.

    Try taking out your quick link and replacing it so that the plate is on the other side. I had this issue with my singlespeeder and a rockguard that was too close for comfort. The link would catch on the edge of the rockguard when I was mashing it.
    Yes, we do indeed rock...http://www.myspace.com/spokedrunkies

  7. #7
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    Do a visual on the rings, I'm sure you probably already have. Make sure the middle ring is still "true" and not bent. I think I still have the scars from when I had a drivetrain slip while hammering out of the saddle. You're kinda like a receiver catching a ball over the middle there - exposed to all kinds of damage!
    I have run SRAM chains before with Shimano rings and they seem to get along fine if everything is acting right. Heck, I have RaceFace rings on a Shimano crank using a SRAM chain and cassette with a Shimano FD and SRAM RD and triggers. Am I a s|ut or what? [SIZE=1](requisite smilie)[/SIZE]
    Big hoopy.
    Turner Sultan / On One Inbred

  8. #8
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    sounds an awful lot like a chainline issue, Ken.

    maybe the spacers on the crankset/external BB

    maybe the derailleur hanger is bent

    maybe the rear der cage is bent

    those are my guesses.

  9. #9
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    Cups are cheap.
    STRAVA: Enabling dorks everywhere to get trails shut down........ all for the sake of a race on the internet.

  10. #10
    Roy
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    I would swap the items you had changed, one at a time, until the problem stopped, then you'll know who was the offender. If you don't have spares, or another ride to borrow them from, nows a good time to get spares. I would swap in this order:

    chain
    cassette
    middle chainring


    Finally, I would double check the tightness of your horst link pivots. When they are loose, they flex noticeably under torque. Actually I would check them first.

  11. #11
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    I've had similar problems with new drivetrains. Mine seemed to be caused by the sticky grease that comes on new chains. It caused chain suck when back pedaling in order to get my cranks in the right position to climb an obstacle on steep hills. This slight backpedal and subsequent mashing on the pedal caused the jump. I would remove the chain and let it soak in dereaseer for a while. Dry it off and apply your normal chain lube.

  12. #12
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    I had that issue some time ago on my Trek Fuel.

    It turns out that it was 2 problems.... The chainline was wrong and the XT middle ring had sharp edges that would catch the chain and drop it onto the small ring.

    It really sounds like you have a chainline issue.

    What rear cog(s) is the chain on when it drops to the middle ring? Is it the biggest cog?

    Shift the chain to the middle ring up front and the middle cog in the rear. Does the chain form a straight line? It should. Can you get the chain to drop from this position while pedaling hard?

  13. #13
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    Yes.

    Quote Originally Posted by Blue Shorts
    I had that issue some time ago on my Trek Fuel.

    It turns out that it was 2 problems.... The chainline was wrong and the XT middle ring had sharp edges that would catch the chain and drop it onto the small ring.

    It really sounds like you have a chainline issue.

    What rear cog(s) is the chain on when it drops to the middle ring? Is it the biggest cog?

    Shift the chain to the middle ring up front and the middle cog in the rear. Does the chain form a straight line? It should. Can you get the chain to drop from this position while pedaling hard?
    It doesn't happen when I'm in a "low torque" gear. So when I'm in the middle/big (in back), it doesn't happen. When I'm in middle/middle it happens.

    Chainline "seems" to be straight. Originally it was off but I changed the spacers on the crankset/BB and it improved the chainline but didn't fix the problem.

  14. #14
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    Quote Originally Posted by gonzostrike
    sounds an awful lot like a chainline issue, Ken.

    maybe the spacers on the crankset/external BB

    maybe the derailleur hanger is bent

    maybe the rear der cage is bent

    those are my guesses.
    I thought so to. Sorry, I didn't provide complete information

    Spacers: quite possibly. What is the correct spacer alignment for a 5-spot. I have 1 spacer on the non-drive side currently.

    DR Hanger: Replaced it.

    Rear DR cage: Very possible. But how likely is it that a misaligned or bent rear DR causes the chain to pop off the middle ring in front? Wouldn't it cause mis-shifting on the cassette?

    I'll replace the rear DR and see if that fixes the problem. Thanks for the advice.

    Ken

  15. #15
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    Quote Originally Posted by Ken in KC
    Spacers: quite possibly. What is the correct spacer alignment for a 5-spot. I have 1 spacer on the non-drive side currently.
    this is not meant to be snarky or mean-spirited...

    the spacer assortment and alignment is whatever gives you the best chainline, meaning whatever enables smooth shifting throughout your range of gear combinations (of course, avoiding the obviously bad super cross-chaining)

    when I installed the Diabolus crankset on my big bike, I had to play around with the spacer assortment to get the best line. it's a bit frustrating, like those brake calipers that use shims instead of the wise Avid CPS system. but in the end, you get a micro-aligned chainline.

    I don't know of a tool to assess derailleur cage alignment, probably the best tool is an experienced eye!

    good luck getting it sorted out, Ken.

  16. #16
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    That's what I thought...

    Quote Originally Posted by gonzostrike
    this is not meant to be snarky or mean-spirited...

    the spacer assortment and alignment is whatever gives you the best chainline, meaning whatever enables smooth shifting throughout your range of gear combinations (of course, avoiding the obviously bad super cross-chaining)

    when I installed the Diabolus crankset on my big bike, I had to play around with the spacer assortment to get the best line. it's a bit frustrating, like those brake calipers that use shims instead of the wise Avid CPS system. but in the end, you get a micro-aligned chainline.

    I don't know of a tool to assess derailleur cage alignment, probably the best tool is an experienced eye!

    good luck getting it sorted out, Ken.
    Why you snarky sob.....

    I originally set up the crankset with the spacers in the same position as it is currently. I'm mentioning the set up only so that people can correct me if I've set it up incorrectly. I set it up myself based on the middle chainring and the middle gear on the cassette.

    Re the rear DR: Do you think that a rear DR out of whack would result in dropping the chain on the front rings? At this point, I'm willing to try anything. I'm heading to CO to ride in a couple weeks and I need to get this figured out. Or ride my SS in CO. Which I'm not capable of doing.

    Ken

  17. #17
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    I'd throw another new middle ring on, just to be sure the "new" one you already are using isn't defective or damaged in some way. Besides, you'll need a new one eventually, so it's worth a try.

    Eliminate the obvious first.......that's an easy one.
    Yes, we do indeed rock...http://www.myspace.com/spokedrunkies

  18. #18
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    Agree. Change the middle ring first. SOmething is wrong...either the ring is moving under stress...or there are burrs...or a tooth is bent...or you have gremlins

  19. #19
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    Quote Originally Posted by Ken in KC
    Why you snarky sob.....

    I originally set up the crankset with the spacers in the same position as it is currently. I'm mentioning the set up only so that people can correct me if I've set it up incorrectly. I set it up myself based on the middle chainring and the middle gear on the cassette.

    Re the rear DR: Do you think that a rear DR out of whack would result in dropping the chain on the front rings? At this point, I'm willing to try anything. I'm heading to CO to ride in a couple weeks and I need to get this figured out. Or ride my SS in CO. Which I'm not capable of doing.

    Ken
    heh. yeah, call me Mr Snark!

    rear der cage that is bent INBOARD from the upper jockey wheel to the lower jockey wheel, as it is viewed from the rear, can cause the chain to want to drop inward toward the little ring from the middle one, or to the middle ring from the outer one.

    when I've had bent der hangers (bent inboard) and bent der cages (also bent inboard) I've had problems at the front (wanting to drop the chain to the smaller chainring) and at the cassette (not being able to index the shifts consistently throughout the range).

    sadly, since I'm not a shop wrench with lots of experience, I learned through trial-and-error by hand-bending der hangers and der cages. sometimes I bent them too far and made things worse. sometimes I fixed them. it helps to have the der hanger alignment tool for the der hanger, of course. but for the cage, I really have no short answer.

    I would try the chainline spacing first.

    then I would try the middle ring IF you have put enough time/mileage on the new middle ring to make it a suspect.

    then I would check the derailleur hanger and der cage.

    beyond that, it's gonna take someone with more wisdom and experience than I have (which isn't too hard to find)

    last suggestion: check the Park Tools website, they have a repair help section that is pretty danged comprehensive.

    +++++++++++++++++++++

    jokermtb and Blue Shorts ... didn't Ken say he just put a new middle ring on the bike?

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