Frame geometery

Discussion in 'Cycling Equipment' started by Colin Marshall, Aug 17, 2004.

  1. Hi,

    I have a frame with a 72 seat angle 57.5 top tube and 55(c-c) seat tube with
    a 120 stem.

    It has been suggested that a 73 seat tube with a 56.5 top tube and a 120
    stem is exactly the same.

    My maths is not that good, are the equivalent?

    Thanks
     
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  2. cpm-<< I have a frame with a 72 seat angle 57.5 top tube and 55(c-c) seat tube
    with
    a 120 stem.

    It has been suggested that a 73 seat tube with a 56.5 top tube and a 120
    stem is exactly the same. >><BR><BR>
    << My maths is not that good, are the equivalent? >><BR><BR>


    Essentially. General rule of thumb is as you change the seattube angle by one
    degree, and moving your saddle forward or aft ro accomodate this to retain
    KOPS, you move it 1cm.



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

    Bruce Frech Guest

    the setback of the toptube and seattube intersection is cos(angle) times
    seattube length. So the difference between a 72 and a 73 seat angle for a
    55 C-C seattube is:

    55cm * (cos(72) - cos(73)) = 0.924 cm, which is close enough to one
    centimeter for your needs.

    Bruce

    "Colin Marshall" <[email protected]> wrote in message
    news:[email protected]
    > Hi,
    >
    > I have a frame with a 72 seat angle 57.5 top tube and 55(c-c) seat tube

    with
    > a 120 stem.
    >
    > It has been suggested that a 73 seat tube with a 56.5 top tube and a 120
    > stem is exactly the same.
    >
    > My maths is not that good, are the equivalent?
    >
    > Thanks
    >
    >
    >
     
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