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  1. #1
    Senior Member philski's Avatar
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    Two-cable IGH spring return a viable option?

    Refer to the diagram below. For a NuVinci n360 you have two shifting cables, the underdrive and overdrive. It seems to be it is possible to use a spring or counterweight to pull the underdrive and then use a conventional shifter for the overdrive (may require modification/consideration for full length of pull). Is there a fundamental reason this couldn't work? Have people tried? A few Googles turned up fruitless.

    The difficulty I can see is the 120mm draw length of the cable. The system may need to be a bit more elegant than a single spring.

    Open to suggestions (I hope this has been done before, success or otherwise)

    Thanks

    philip

    IGH spring.jpg

  2. #2
    coprolite fietsbob's Avatar
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    your lever would need a capstan circumference of 5 inches or take multiple revolutions... (that 12cm)..

    how about a pully , 2 housing frame stops, and a loop of cable.. will do the job, I suspect ..

    use a bare cable run and attach a ball to it to pull /push

    or a big ol' stingray shift lever to pull .. with the distance to lever pivot say 3~4x the cable pull ..

    of course, a servo motor could turn that capstan and then you just need a rocker control button
    or up/down pair. and a battery ,,
    Last edited by fietsbob; 01-21-14 at 10:47 AM.

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