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Rear derailleur question - bolt and cable

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  • 08-07-2020 10:58am
    #1
    ILIKEFOOD
    Registered Users Posts: 681 ✭✭✭


    Hi All

    Pulling out my hair trying to sort my gears...

    Cable snapped so i got a new one.. using a very good park tools vid on youtube to guide me in my attempt at tuning up my gears.

    One thing I'm not sure about is how tight should the rear cable be pulled and secured by the cable bolt?

    Gears are roughly shifting but I can't seem to fine tune without the chain failing to get to the smallest cog...I feel as if the derraileur isn't being pulled out enough to allow it despite following the guide for adjusting the H limit screw. Fiddling around with the barrell adjuster etc..

    I'm wondering if the cable is too tight or loose and if so what kind of tension should be on it? Could it be something else? Also wondering about worn out cassette (about 10k on it - chain replaced in the last year) but it doesn't look worn when compared to the one I used on my barely used turbo wheel..

    I have The Spokesman coming to me anyway in the next day or two to give it a proper look but it's driving me mad.

    Any tips and tricks much appreciated..

    Edit: It's Ultegra 6800 if that makes any difference

    C


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    #2
    cletus
    Registered Users Posts: 7,997 ✭✭✭cletus


    Theres a couple of different things it could be. There should be slack on the cable when on the smallest cog

    Video below goes through some trouble shooting ideas



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    #3
    07Lapierre
    Registered Users Posts: 8,245 ✭✭✭07Lapierre


    "I can't seem to fine tune without the chain failing to get to the smallest cog"
    sounds like the cable is too tight.

    Undo the bolt clamping the cable to the derailleur. spin the pedals and the chain should drop onto the smallest sprocket.
    once its on the smallest sprocket ensure the barrell adjuster is set to the middle position.
    then pull the cable with your fingers and tighten the bolt.
    Spin the pedals and move the shifter to put the chain on the next sprocket. If needed, use the barrell adjuster to fine tune as needed.


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    #4
    Whatwicklow
    Registered Users Posts: 680 ✭✭✭Whatwicklow


    Make sure your clicked to the smallest gear
    Open the nut holding the wire
    Pedal the derailleur on the the second gear but don't shift
    Place cable ans tighten nut (no added tension)
    Close to perfect shifting


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    #5
    triggermortis
    Registered Users Posts: 2,684 ✭✭✭triggermortis


    With the cable not screwed down, the chain should go to the smallest cog. If it doesn’t, then you need to adjust the limit screw. There’s one for Each of the upper and lower limits. The park tools and GCN videos are very good for showing what you need to do at this point.
    Once these are set it’s a matter of adjusting your cable tension


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    #6
    The Noble Nudge
    Registered Users Posts: 1,616 ✭✭✭The Noble Nudge


    A job I'm considering taking on very very soon..........
    The slightest turn is sometimes a bit too much from previous attempts the bike is a lot more delicate!
    Make sure all the debris from old cable is/was removed and a light drop of synthetic dry lube on the cable before fitting was told by the lads in the shop told me (and no it wasn't a sex shop or was it all sounds very erotic!) :D


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    #7
    Type 17
    Registered Users Posts: 2,730 ✭✭✭Type 17


    ILIKEFOOD wrote: »
    ...I feel as if the derraileur isn't being pulled out enough to allow it despite following the guide for adjusting the H limit screw. Fiddling around with the barrell adjuster etc...

    Note that the cable pulls the derailleur in (towards the biggest sprocket), not out. The outward direction is done by a spring inside the parallogram body of the derailleur. Understanding this will help you understand which way to turn the barrel adjusters, etc.

    1. Loosen cable pinch bolt
    2. Whilst holding the loose end of cable gently, work the shifter all the way in, then all the way out - does the cable pay out as smoothly as it gets drawn in? If not, your cable housing is dirty/gummed up and needs replacing.
    3. Pedal bike to bring derailleur to smallest sprocket
    4. Check H screw as per Park Tool or similar video (Shimano's setting is: centre of upper jockey wheel is under the outer edge of the smallest sprocket).
    5. Screw in barrel adjuster fully, and then back out about 1.5 turns
    6. With cable fully released (top gear), grab the end of the cable and hold it taught (taught, but not hurt-your-fingers tight).
    7. Tighten cable in pinch bolt.
    8. Try shifting up and back down the cassette - open the barrel adjuster a quarter-turn at a time if the chain won't climb.
    9. Cable-test - if it it can only be adjusted to shift in (towards the spokes) nicely, but then won't shift out nicely, the cable is probably sticky (or the chain is worn)


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