more indexing questions

Discussion in 'Cycling Equipment' started by Walter Mitty, Jul 12, 2003.

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  1. Walter Mitty

    Walter Mitty Guest

    ok, here goes ...

    I'm confused again. I thought I'd understood all the issues with camapg/shimano indexing
    compatabilitiy.

    But maybe I'm overthinking or underthinking or something ...... (deep breath) ....

    You can use a Shimano 9 sp cassette with a campag 9 spd derailleur using campag 9 speed shifters. So
    far so good.

    But, since the derailleur itself is not "indexed", and the levers do the work, and it IS a shimano
    hub, WHY doesn't a shimano rear derailleur just "work". Surely the shifting distances are the same
    since its the same hub.

    I know this is going to be glaringly obvious.

    --
    Walter Mitty.
     
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  2. A Muzi

    A Muzi Guest

    "Walter Mitty" <[email protected]> wrote in message news:[email protected]...
    >
    > ok, here goes ...
    >
    > I'm confused again. I thought I'd understood all the issues with camapg/shimano indexing
    > compatabilitiy.
    >
    > But maybe I'm overthinking or underthinking or something ...... (deep breath) ....
    >
    > You can use a Shimano 9 sp cassette with a campag 9 spd derailleur using campag 9 speed shifters.
    > So far so good.
    >
    > But, since the derailleur itself is not "indexed", and the levers do the work, and it IS a shimano
    > hub, WHY doesn't a shimano rear derailleur just "work". Surely the shifting distances are the same
    > since its the same hub.

    The rear changer is a paralellogram that translates wire pull across the corners into a lateral
    motion at the cage. The ratio of cable movement in to cage travel out is not identical. That's
    the reason that switching the wire to the "wrong" side allows some changers to work where they
    were not intended. That changes the leverage of the wire and therefore the ratio of wire travel
    to cage travel.

    --
    Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971
     
  3. Walter Mitty-<< You can use a Shimano 9 sp cassette with a campag 9 spd derailleur using campag 9
    speed shifters. So far so good.

    But, since the derailleur itself is not "indexed", and the levers do the work, and it IS a shimano
    hub, WHY doesn't a shimano rear derailleur just "work". Surely the shifting distances are the same
    since its the same hub.

    I know this is going to be glaringly obvious.

    The amount the rear der moves for each 'click' is determined by the diameter of the barrell the
    cable is being wrapped around in the shifter and the dimension of the rear der. If these were the
    same shimano and Campagnolo, they would be cross compatible but they are not.

    Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
    (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"
     
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