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  1. #1
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    Rear Derailleur Problem

    Alright, I think I know what's at fault, but I'd like to do a blind study....

    Shifting on the middle cogs ( but closer to the biggest than the smallest) is less than desirable. Hesitation, skipping, overshifting, etc. Shifting to and from the largest cog is flawless and same deal with the smallest cogs. No amount of adjustment to limit screws or barrels seems to cure the problem.

    Thoughts?

    Thanks.

  2. #2
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    Quote Originally Posted by notrelatedtoted
    Shifting on the middle cogs ( but closer to the biggest than the smallest) is less than desirable. Hesitation, skipping, overshifting, etc. Shifting to and from the largest cog is flawless and same deal with the smallest cogs. No amount of adjustment to limit screws or barrels seems to cure the problem.
    One or more of the following: gummed up cable housing; frayed derailleur cable; bent derailleur hanger.

  3. #3
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    Did the bike ever shift right? If so when did the problem start? After a crash...new parts...ect? This could lead you to the problem.

    This one is tough to diagnose from just a post but I've had a few problems like this once.

    First thing is check the derailleur hanger and make sure it's straight. Put the bike on a stand and look from the back. A small bend can throw off the geometry and cause the problems you mentioned.

    Also, try taking up some cable slack by turning the shifter barrel adjuster not the one at the derailleur. Sounds like it starts to shift better as the chain moves up the cassette which may mean there is too much slack in the cable (or too much tension depending on which direction the cable moves your specific derailleur). For example, if your cable pulls the derailleur up the cassette, add tension, if it pulls it down the cassette, try adding a click or two of slack.

    That's all I can think of.

    Good Luck
    Jim

  4. #4
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    I think you guys got it...

    I think my derailleur hanger is bent, ever so slightly. The shop didn't think so, but ultimately, that's gotta be it. Cables are good, etc. Thanks, all. Just wanted to make sure I wasn't crazy, because the bend isn't too obvious....

  5. #5
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    A small bend can do it. I had one that was staight side to side but was stretched back some how and it screwed my shifting up and no adjustment could fix it. If your gentle you can bend it back but just make small movements and test.

    Jim

  6. #6
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    And it'll be really hard to get it really straight without a tool to check alignment and do the bending like the Park DAG1
    "...the people get the government they deserve..."
    suum quique

  7. #7
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    Hanger tool

    Yes, you do need a tool to straighten the der hanger. Many times you just don't know which way to bend it. Just look at the Park tools website and you'll see how to make it. All it really is, is a pry bar. I made mine out of a piece of scrap metal and an old der bolt. I used a piece of aluminum C-channel 1 1/4" X 1 1/4" and drilled a hole in one end for the der bolt. When you attach it to the hanger,you need to use a few flat washers as spacers so the bar does not hit the frame when you rotate it. It works great! I've used it about fifteen times now.I just use a ruler to measure instead of a gauge. You could also use steel instead of aluminum.

  8. #8
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    Personally I use a machinists rule. Always works for me.

  9. #9
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    For $10.00

    I'll just order a new hanger and pick up a spare or two.

  10. #10
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    Quote Originally Posted by fred3
    Personally I use a machinists rule. Always works for me.
    How do you determine a hanger is in alignment with a machinist's rule? What do you use to bend it straight?
    "...the people get the government they deserve..."
    suum quique

  11. #11
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    Even new hangers can be slightly crooked...

    Quote Originally Posted by notrelatedtoted
    I'll just order a new hanger and pick up a spare or two.
    We were having shifting problems on one of the bikes that I maintain. It looked to us like the derailleur hanger was bent, so I purchased a new one and installed it. Shifting performance improved somewhat, but there were still problems. Eventually, I purchased a Park DAG-1 and found that the new hanger was out of alignment. The shifting problems were cured after aligning the hanger using the DAG-1.

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