Indexing w/o slant parallelogram?

Discussion in 'Cycling Equipment' started by Vega, May 8, 2003.

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  1. Vega

    Vega Guest

    Well, maybe it's just a silly question, BUT I think i've seen some Shimano derailleurs (cheap
    models, but new, mounted on some "city bikes" with indexed shifting system) with a straight (not
    slant, I mean) parallelogram. Is it possible? Or just my mistake? Could they work well?
     
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  2. vega-<< but new, mounted on some "city bikes" with indexed shifting system) with a straight (not
    slant, I mean) parallelogram. Is it possible? Or just my mistake? Could they work well?

    They are made slant parallogram with that L shaped mounting bracket that moves the der forward and
    up, W/o that bracket, they probably wouldn't index.

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

    Ron Hardin Guest

    I remember before Sun Tour figured out the geometry of the slant parallelogram, when derailleurs
    never worked for long. The Huret Allvit, I think it was, was the obvious geometry you needed and it
    always gunked up right away.

    Then the Sun Tour came out and you could also use it to drive tent pegs.

    I doubt they'd go back.

    Side note on indexing: having modified my SRAM MRX broken index shifter to be a friction shifter (by
    adding friction underneath) I'm actually quite happy with it. You don't miss indexing once you
    arrange it to stay put where you set it. The shifts are quieter and easier.
    --
    Ron Hardin [email protected]

    On the internet, nobody knows you're a jerk.
     
  4. Jim Adney

    Jim Adney Guest

    On Thu, 08 May 2003 10:18:56 -0400 Ron Hardin <[email protected]> wrote:

    >I remember before Sun Tour figured out the geometry of the slant parallelogram, when derailleurs
    >never worked for long. The Huret Allvit, I think it was, was the obvious geometry you needed and it
    >always gunked up right away.
    >
    >Then the Sun Tour came out and you could also use it to drive tent pegs.

    A Huret Alvit was also my first derailleur, but I think it's fair to say that the Alvit was the one
    you could use to drive tent pegs. ;-)

    -
    -----------------------------------------------
    Jim Adney [email protected] Madison, WI 53711 USA
    -----------------------------------------------
     
  5. I believe the "slant" you are referring to is the angle that allows the derailleur to follow the
    profile of the cogs.

    On a straight derailleur (do they still make those?) the jockey roller (the top one that actually
    shifts the chain) would probably get to far away from the cogs to index .

    If memory serves, they barely shifted, period.

    May you have the wind at your back. And a really low gear for the hills! Chris

    Chris'Z Corner "The Website for the Common Bicyclist": http://www.geocities.com/czcorner
     
  6. Chris-<< If memory serves, they barely shifted, period.

    Altho not the 'automatic transmission' type of shift with indexing, friction shifters and
    'straight'rear ders work just fine. I use a C-Record rear der, 7s Regina America freewheel and
    friction shifters and I have no problem finding gears.

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

    Ron Hardin Guest

    Qui si parla Campagnolo wrote:
    >
    > Chris-<< If memory serves, they barely shifted, period.
    >
    > Altho not the 'automatic transmission' type of shift with indexing, friction shifters and
    > 'straight'rear ders work just fine. I use a C-Record rear der, 7s Regina America freewheel and
    > friction shifters and I have no problem finding gears.

    The trouble with the Huret Alvit was that it gunked up, so would not upshift at all, very soon. The
    geometry of the slant Sun Tour solved that; it continued to work in normal use, not predictably
    failing in a week.

    Friction shifters are fine.
    --
    Ron Hardin [email protected]

    On the internet, nobody knows you're a jerk.
     
  8. Andymorris

    Andymorris Guest

    Chris Zacho "The Wheelman" wrote:
    > On a straight derailleur (do they still make those?) the jockey roller (the top one that actually
    > shifts the chain) would probably get to far away from the cogs to index .
    >
    > If memory serves, they barely shifted, period.
    >

    But they were superb Italian engineering, so it was the users fault.

    --
    Andy Morris

    AndyAtJinkasDotFreeserve.Co.UK

    Love this: Put an end to Outlook Express's messy quotes
    http://home.in.tum.de/~jain/software/oe-quotefix/
     
  9. A Muzi

    A Muzi Guest

    "Chris Zacho "The Wheelman"" <[email protected]> wrote in message
    news:[email protected]...
    > I believe the "slant" you are referring to is the angle that allows the derailleur to follow the
    > profile of the cogs.
    >
    > On a straight derailleur (do they still make those?) the jockey roller (the top one that actually
    > shifts the chain) would probably get to far away from the cogs to index .
    >
    > If memory serves, they barely shifted, period.

    That's a bit of an overstatement, even allowing that Suntour's slant parallelogran design is
    superior. (My Svelto on a twelve tooth range front and back, f'rinstance)

    --
    Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971
     
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