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  1. #1
    Squawk 7700
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    Santa Cruz Butcher - Drivetrain issues - chain

    https://www.dropbox.com/sh/jzwq8fo5r5ahd7h/KWe2QJROQr

    Hi all,
    I posted an album above of my SC Butcher.

    I measured the chain length and I know I'm not far off. I used the method of largest cog / largest chain ring plus 2. I think that's pretty standard from what I've read.

    The rear derailleur is shimano XT. When I'm in the smallest cog / smallest chain ring, I get a slack in the chain. I'm pretty sure the derailleur only goes on one way reference to the hanger.

    Can anyone help me out with any tips to take up the slack? I will take a pic of the chain in the largest cog / chainring combo and include it in the album just to make sure the derailleur cage is in the correct position. I'm almost certain that removing anymore links would put too much tension on a bigger gear combo.

    Thanks in advance. I'm a noob mechanic.

  2. #2
    Senior Member mrrabbit's Avatar
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    1. You are always going to have tension in the big gear combo...

    2. I typically install a chain (in terms of length) by starting out as follows:

    - run chain in the small +small positon.
    - allow rear derailleur to completely relax.
    - position both ends of chain such that derailleur is still relaxed.
    - pull one link too see if rear derailleur begins to experience spring tension.

    That's the position that I'll decide to link the chain...

    Not "official" way as far as I know, just how I typically do it.

    =8-)
    4000+ wheels built since 1984...

    Disclaimer:

    1. I do not claim to be an expert in bicycle mechanics despite my experience.
    2. I like anyone will comment in other areas.
    3. I do not own the preexisting concepts of DISH and ERD.
    4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
    5. My all time favorite book is:

    Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life

  3. #3
    Senior Member mrrabbit's Avatar
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    Have a question:

    Are you mixing "compact" drive train components with "non-compact" drive train components?

    =8-)
    4000+ wheels built since 1984...

    Disclaimer:

    1. I do not claim to be an expert in bicycle mechanics despite my experience.
    2. I like anyone will comment in other areas.
    3. I do not own the preexisting concepts of DISH and ERD.
    4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
    5. My all time favorite book is:

    Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life

  4. #4
    Senior Member mrrabbit's Avatar
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    Also, I'm used to seeing the rear derailleur pulley cage running parallel with the ground when it the relaxed position...is it installed correctly?

    =8-)
    4000+ wheels built since 1984...

    Disclaimer:

    1. I do not claim to be an expert in bicycle mechanics despite my experience.
    2. I like anyone will comment in other areas.
    3. I do not own the preexisting concepts of DISH and ERD.
    4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
    5. My all time favorite book is:

    Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life

  5. #5
    Senior Member
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    Quote Originally Posted by mrrabbit View Post
    Have a question:

    Are you mixing "compact" drive train components with "non-compact" drive train components?

    =8-)
    From the pictures, the OP has a non series Shimano (probably M542 or M543) crank, and XT F & R Mechs, hard to tell the model of the cassette; looks to be either a 34t or 36t max . All of these will be compact, Standard /non-compact hasn't been used for MTB's since the very early 1990's so not an issue here.

  6. #6
    biked well well biked's Avatar
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    Quote Originally Posted by highflyr View Post

    I measured the chain length and I know I'm not far off. I used the method of largest cog / largest chain ring plus 2. I think that's pretty standard from what I've read.
    My guess is that when you did the big/big chain sizing method, you didn't do it exactly like this. http://www.sheldonbrown.com/derailer...ent.html#chain

    Read it carefully, including the part about bypassing the rear derailleur. This will give you the shortest chain length that is still long enough to safely shift to big/big. My guess is that if you follow Sheldon's instructions carefully, you'll be able to shift to big/big with no problems (this is the MOST important criteria in sizing a chain) and your chain slack will go away in small/small.

  7. #7
    Senior Member mrrabbit's Avatar
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    http://techdocs.shimano.com/media/te...9830746412.pdf

    Shimano's PDF for a RD-M780. Shimano's docs are pretty darn good...be sure to read the small "B" tension screw instructions - and front chain ring tooth difference max. Other than that, jmc101, well biked...

    =8-)
    4000+ wheels built since 1984...

    Disclaimer:

    1. I do not claim to be an expert in bicycle mechanics despite my experience.
    2. I like anyone will comment in other areas.
    3. I do not own the preexisting concepts of DISH and ERD.
    4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
    5. My all time favorite book is:

    Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life

  8. #8
    Squawk 7700
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    Thanks for the pdf file. It's the same one that I had followed to determine chain length along with sheldon brown's page.

    If you look at the big / big combo, there is still room for me to remove a couple more links and that should remove the slack in the small / small combo.

    I also looked at the pics here - http://www.pinkbike.com/news/Tech-Tu...sics-2012.html and it appears that their 'just right' chain length in the big / big combo allows me to still remove a couple links. It just contradicts the way the length of the chain is supposed to be measured.

    I'm positive I installed the rear der correctly. There is a tab on the hanger and I mounted the rear der right against it as per the manual.

    I've got one SRAM quick connector left so I'm going to take out another couple links and post an update.

  9. #9
    Squawk 7700
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    Thanks for all your help.

    I removed 2 more links and everything worked out fine.

  10. #10
    Senior Member mrrabbit's Avatar
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    Your welcome...happy riding.

    =8-)
    4000+ wheels built since 1984...

    Disclaimer:

    1. I do not claim to be an expert in bicycle mechanics despite my experience.
    2. I like anyone will comment in other areas.
    3. I do not own the preexisting concepts of DISH and ERD.
    4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
    5. My all time favorite book is:

    Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life

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