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  1. #1
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    Easy derailleur install question/chain interface

    So I'm working on my first ground-up build ever and this is my first time installing a RD or even messing with it.

    I have the chain installed, installed and adjusted my FD and now have cabled my RD but didn't crimp it down or anything because I noticed that it's in the 3rd smallest cog and it somewhat naturally wants to be in that cog. Is that normal? Should I go ahead and continue or how should I overcome this?

    The RD cable isn't under any tension, isn't even clamped down with the bolt and I am worried about this because I was under the impression that the limits should be adjusted from smallest to biggest cog and the tension/indexing would screw up if the start is the 3rd smallest cog.

    I tried manually manipulating the RD/chain to the smallest cog like the instructions said. Unfortunately, with that, and with any pedaling, it naturally goes to the 3rd gear. I didn't touch the limits yet.

  2. #2
    Senior Member JonathanGennick's Avatar
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    Quote Originally Posted by flashpoint145 View Post
    ...s that normal? Should I go ahead and continue or how should I overcome this?
    I would double-check the hanger-alignment first. Yes, even on a brand new build. (My experience is that the derailleur doesn't usually default to a cog that far inboard).

    Then unscrew the high-limit screw whilst pedaling the bike in the stand. Unscrew until the chain drops into the smallest cog. You may need/want to unscrew a bit beyond that get a good adjustment. I like to have my limit just a tad to the outside, and then I take up that tad using the barrel adjuster.

    Have you read a procedure yet for adjusting a rear derailleur? Park Tools has one on their site.

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    Quote Originally Posted by JonathanGennick View Post
    I would double-check the hanger-alignment first. Yes, even on a brand new build. (My experience is that the derailleur doesn't usually default to a cog that far inboard)

    Have you read a procedure yet for adjusting a rear derailleur? Park Tools has one on their site.
    Yes that is where I realized I had the problem the instructions that came with the RD said to have the chain in the smallest cog
    Shimano ultegra 6700 But the instructions are still iffy

  4. #4
    Senior Member JonathanGennick's Avatar
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    Quote Originally Posted by flashpoint145 View Post
    Yes that is where I realized I had the problem the instructions that came with the RD said to have the chain in the smallest cog
    Shimano ultegra 6700 But the instructions are still iffy
    This article might prove helpful:

    http://www.parktool.com/blog/repair-...nts-derailleur

    I'm not really a big fan of Park's Painful Step-by-Stepness, but they know what they are doing and their process will be solid.

  5. #5
    Senior Member JonathanGennick's Avatar
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    Some quick notes:

    * The high-limit sets the starting point for the indexing.

    * The low-limit has nothing to do with the actual shifting between gears.

    * Get the high-limit and cable-tension right, and the shifter does the rest.

    So a really simplified process is:

    1. Set the high-limit so the chain is centered on the smallest cog.

    2. Set the low-limit so that you cannot push the chain into the spokes.

    3. Connect cable. Pull lightly with fingers to remove slack.

    4. Do some test shifts. Add tension as needed with barrel adjuster.

    Sometimes after a few test shifts I need to unbolt the cable and pull a bunch of slack, and then rebolt the cable.

    Often in step 1 I will leave the chain a tad towards the outside of center so that I have some room to play around in both directions. Depends upon my mood at the time.

    Hanger alignment is crucial. Trouble getting the adjustment correct is almost always down to a bent hanger. Otherwise, given decent-quality and not-overly-worn parts, the above process gets me where I need to be.

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    Thanks a million. Ill update when i get home tomorrow

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