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Thread: Cable tightness

  1. #1
    Schleckaholic K&K_Dad's Avatar
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    Cable tightness

    How much slack, if any,should be in the fd cable? Should it be reasonably snug or should it have some slight slackness (cool word) to it.

    Thanks in advance.

    Edit: I should have said , "When it's in the smallest chain ring".
    Last edited by K&K_Dad; 08-07-08 at 10:26 AM.
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    No slack. Put the shifter in its lowest position before attaching to the derailleur. It's common to need to add a bit of tension to the cable for ideal shifting.

    Al

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    Don't know that it matters. By definition, if your low limit stop engages then there will be some slack. I think people with doubles in particular rely on the limit stops more than the index. Of course, if it has too much slack then more of your upshift will be taken up by the slack, and it might not shift well.

    But it's not necessarily a problem if it's not under tension when in the small ring. If the thing shifts right, then it's good.

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    A little slack would be OK as long as the shifter is able to take up enuff cable to go to the big ring. But why make your fingers do MORE work? Make it taunt, then minimum lever travel, and it will feel precise, and the lever resitance will be constant. Plus slack cable makes yer bike look like a turkey's flap. Enuff reasons?

  5. #5
    Rat Bastard mcoomer's Avatar
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    I may be misremebering, but I seem to recall that the Shimano instructions for the Dura Ace fd have you adjust the L limit screw prior to even clamping on the shift cable. After that, shift to the large ring and adjust the H limit screw. I also seem to recall that Park Tool tells you to pull the cable tight by hand when setting the H limit to ensure that the fd is actually hitting the screw. After making your adjustments you should be able to shift from small to large ring with no trouble and with only a slight amount of tension on the cable in the small ring.
    It's better to burn out than fade away...or slip out of your pedal and face plant on the side of the road!!!

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    You'll get all the potential slack you need by screwing the barrel adjuster all the way in, then back it out 3/4 to 1 full turn before setting the cable in the pinch bolt. Pull all the slack out and tighten. bk

  7. #7
    Your mom
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    How much slack is determined by what you need your FD to do. There's no right answer, only the situation that works for your setup.

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    Quote Originally Posted by tellyho View Post
    How much slack is determined by what you need your FD to do. There's no right answer, only the situation that works for your setup.
    OK I'll bite.

    I want my FD to shift precisely, no play, no shimmy, ideally, minimum pressure/minimum travels from my fingers and BAM! (like feathertouch electronics controls or as close as one can get), and pressure to my fingers is to remain constant, so no slack-then-hard.

    How much slack?

    If OP has a tripple, never mind, I digress, am out!
    Last edited by jsmithepa; 08-07-08 at 11:14 PM.

  9. #9
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    Indexed or not?

    If you have a non-indexed shifter (i.e. old stuff, bar-end or downtube shifter), then it doesn't matter because the limit screws will limit the derailleur movement. Considering that the shifter is able to shift through 4 rings (verified) or maybe 5, you would need a lot of slack in the cable before it would actually prevent you from shifting all the way to the large cog.

    If you have an indexed shifter (i.e. STI, Rapidfire... and a lot of new stuff), then I think you should keep a weeny tiny little amount of slack in the cable, and then take all the slack away with the adjusting screw. How much? Enough that the cable isn't loose anymore, but not enough that you start moving the derailleur. How to check? Basically check with the middle gear. If you take too much or too little slack, the derailleur won't be properly aligned when you shift in the middle ring.
    Michel Gagnon
    Montréal (Québec, Canada)

  10. #10
    Senior Member DannoXYZ's Avatar
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    I usually have zero-slack in the FD cable. I use it to position the FD at its inner-most position, no relying on the inner limit-screw at all. That way, as soon as I pull on the lever, the FD moves outwards.

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