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  1. #1
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    Mendon Dan Tony: XT Crank / Prophet ??

    Guys,

    Recently installed a new XT Crank/chain/rear tire/cassette/XT RD on my prophet.

    Everything seems to shift fine, especially on the work stand.

    When I am cresting a hill, especially out of the saddle, when the rear suspension is active, the chain seems to be jumping / skipping off the FRONT chainrings, sometimes even dropping from middle to small.

    When I installed the crank set, there was a spacer section that I followed in the shimano instruction sheet. It showed a small spacer for the front derailleur that was not in the kit, (looked like it went somewhere above, on the tube clamp?), so seeing I didn't have the spacer, I went ahead and put the bearing spacer on the outside of the e-type derailleur bracket down at the bottom bracket interface.

    Could this be causing my issues, is the chain line far enough off seeing the spacer is outside the derailleur bracket instead of inside? I can see it causing minor front shifting issues but the skipping stuff has me scratching my head.

    If I do need the small spacer, where would I source one? Would a couple of washers work in a pinch?

    thanks,
    Jim

  2. #2
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    Chain skips when hitting bumps, while the swingarm is compressed? Is your front and rear derailleurs adjusted correctly? Does the rear one provide enough tension on the chain? Is the chain too long? New chains are always too long, gotta take off a few links usually.

    My memory is not good enough to remember what spacers go where with the XT crank on the Prophet, I can check tonight if someone else hasn't confirmed yet or better, check on Cannondale's web site in the Tech section, there is a document called Prophet Front derailleur setup guide or something like that. it gives the correct way to place the spacers with the different cranks and front derailleurs combo...

    DAN.GEROUS.NET : MOUNTAIN BIKING : CYCLOCROSS : ROAD :

  3. #3
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    My initial inclination is the chain being too long. When I swapped it, I placed it side by side with the original, so I am within a link or two of it.

    Do you think going from a low normal to top normal spring XT rear derailleur would also require less links?

    thanks for the reply Dan, I'll also go hit that link for more info.

  4. #4
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    No, low-normal vs top-normal, both should use the same chain length but... are both derailleurs long cage? Medium and short cage derailleurs would require shorter chains... Another thing, not sure if it helps or not but the front e-type derailleur has two height settings, it should be at it's lowest position on the Prophet.

    DAN.GEROUS.NET : MOUNTAIN BIKING : CYCLOCROSS : ROAD :

  5. #5
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    Dan, both XT rear derailleur's are the long cage.

    I haven't messed with the front derailleur at all other than adjusting cable tension.

    Just looked over the spacing requirements, and the picture appears to be the same as the one in the Shimano instructions. It would appear I am missing a spacer that came with the LX front derailleur that wasn't used for the Truvativ setup from the factory. So my spacer is likely in a parts bin in some dark closet at Cannondale....

    BUT, I have the LX, and the diagrams all indicate XT derailleurs, but I'll assume they are the same, so my spacers are incorrectly placed/missing. Looks like I might just have to pick-up an XT front.

    I'll change the spacer first, than look at the chain length if need be.

    thanks!

  6. #6
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    Front derailleur model year

    Check your model year of the front derailleur. The spacer placement changed from 2004 to 2005 front derailluer.

    You also can't rely on year of the Prophet to determine the year of the front derailluer. My friend bought a brand new 2005 Prophet that came with a 2004 model year derailleur.

    Compare your derailleur with the diagram Dan referred to at the Cannondale site. The top cage is bigger on the 2005 from the side view.

    If you can't tell then post a closs-up picture from the side view of the front derailleur.

  7. #7
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    Will do, I also have an 05 prophet, so maybe I have the old FD as well.

    Gracias!

  8. #8
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    Quote Originally Posted by JimThomas
    Will do, I also have an 05 prophet, so maybe I have the old FD as well.

    Gracias!
    Yup, 04 LX model front derailleur. Spacers in the wrong places, hopefully the misaligned chainline is the ONLY issue.

    Thanks Dan and Racer0!

  9. #9
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    Hey folks,

    So, new chain (length determined large chainring, large rear cog +1), new rear der., new cassette, new rear wheel, new cable, new cable housing, new der hanger, new XT Crankset with proper spacing for the 04 front derailleur.

    The skipping, ghost shifting problem seemed to decrease in frequency but it still occurs.

    What else am I missing? Everything was fine for about 1.5 years until I tweaked the stock XT rear mech.

    Step 1 replace rear mech and hanger
    Step 2 replace rear wheel and cassette and chain
    Step 3 re-install XT crankset per advice above
    Step 4 replace rear mech cable/housing (complete housing from shifter to mech).
    Step 5 reverify chain length, take out one link



    I do notice that the b spring tension adjustment doesn't move the derailleur (I only have it in about 1/2 way, should I keep screwing it in increasing tension?) Could it be the tension? Does the b spring control how stiff the der. keeps the chain? The chain does seem to slap around more with the new reverse spring derailleur.......

  10. #10
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    Quote Originally Posted by JimThomas
    The skipping, ghost shifting problem seemed to decrease in frequency but it still occurs........
    Is this the front or rear or both???????

  11. #11
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    Quote Originally Posted by racerzero
    Is this the front or rear or both???????
    That's just it, I'm not 100% certain, I think it's just the rear.

  12. #12
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    Does it do this in all the chainrings, or only the middle/small/large rings? I and many others had problems with shimano middle rings casuing a skip, this may be your issue.

  13. #13
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    Quote Originally Posted by Jay04cobra
    Does it do this in all the chainrings, or only the middle/small/large rings? I and many others had problems with shimano middle rings casuing a skip, this may be your issue.

    I mostly ride in the middle chain ring, so this could be it. I will try and pay more attention tomorrow morning. What did you replace the shimano rings with?

    thanks!!

    jt

  14. #14
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    I have steel chain rings on order to replace the middle and small aluminum ones on the XT crankset.

    I tightened the b-spring tension all the way and it helped quite a bit, but still skipping on the rough stuff while pedaling.

    I looked at the stock chain ring, and the middle one's teeth don't stick out above the chains rollers like they do on the small and large chain ring.....

    Airbomb.com -
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  15. #15
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    Quote Originally Posted by JimThomas
    I mostly ride in the middle chain ring, so this could be it. I will try and pay more attention tomorrow morning. What did you replace the shimano rings with?

    thanks!!

    jt

    I got a new chainring from Shimano under warranty. They were supposed to fix this problem, but I suppose it is possible you got an older crank that was sitting on a shelf somewhere. New chainring solved the problem for me a at least 2 of my buddies that I'm sure of.

  16. #16
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    The solution to all those type of problems;
    http://www.rohloff.de/en/products/speedhub/index.html

    Seriously , check if your chainline is OK
    Standard is 47.5 mm
    "There is a big difference between kneeling down and bending over" -FZ

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