Stem Angle Question

Discussion in 'Cycling Equipment' started by Rrgmrg, Jan 22, 2003.

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  1. Rrgmrg

    Rrgmrg Guest

    I am trying to choose between two stems for a new road bike that I am putting together (head tube
    angle of 73.5 degrees). One stem is listed as -10 degrees (Deda), one as 80 degrees (ITM). I'm
    confused. What's the difference ? Which one will result in higher/closer bars ? What stem angle will
    result in a stem that is parallel to the ground, 16.5 ? How much does a 10 degree difference affect
    the reach to the bars ?

    Thanks in advance,

    Randy
     
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  2. Randy, I believe in your case, both stems are the same! Typically stem angles are measured
    perpendicular from the steer tube. A stem with a 0 degrees is perpendicular. By some manufacturers
    the same angle of stem would also called a 90 degree angle. Therefore a Deda stem with a -10 degree
    (-10 from perpendicular) would have an 80 degree angle, the same as the ITM. Understand? Confused?

    "rrgmrg" <[email protected]> wrote in message news:[email protected]...
    > I am trying to choose between two stems for a new road bike that I am putting together (head tube
    > angle of 73.5 degrees). One stem is listed as -10 degrees (Deda), one as 80 degrees (ITM). I'm
    > confused. What's the difference ? Which one will result in higher/closer bars ? What stem angle
    > will result in a stem that is parallel to the ground, 16.5 ? How much does a 10 degree difference
    > affect the reach to the bars ?
    >
    > Thanks in advance,
    >
    > Randy
     
  3. Pete Biggs

    Pete Biggs Guest

    rrgmrg wrote:
    > I am trying to choose between two stems for a new road bike that I am putting together (head tube
    > angle of 73.5 degrees). One stem is listed as -10 degrees (Deda), one as 80 degrees (ITM). I'm
    > confused. What's the difference ?

    None, they're just different ways of describing the angle. 90 degrees is aka 0.

    > What stem angle will result in a stem that is parallel to the ground, 16.5 ?

    -16.5 or 73.5.

    > How much does a 10 degree difference affect the reach to the bars ?

    That's one for the mathematicians :) Will make slighltly shorter. Don't forget the height you set it
    at will make a difference to reach too, so take into account how much steerer there is to play with
    (<- assuming threadless ->). If it's cut short, you may well have to use a positive rise stem, ie.
    greater than 90 degrees. This angle can also be obtained by flipping a negative rise stem, eg. an 80
    upside down becomes a 100.

    I know it's difficult to calculate what you need. I'm going through the same thing at the moment.

    ~PB
     
  4. Scic

    Scic Guest

    >From: "rrgmrg" [email protected]

    > What stem angle will result in a stem that is parallel to the ground, 16.5 ?

    Correct. A head tube of 73.5 and a stem of (minus) 16.5 will give you a stem parallel to the ground.

    > How much does a 10 degree difference affect the reach to the bars ?

    Very little. You can get a rough approximation of the change by holding a ruler perpendicular to the
    head tube and dropping a plumbed line down from the clamp face to the ruler. Re-mount stem upside
    down and do the same.

    Sig Chicago
     
  5. Mark Hickey

    Mark Hickey Guest

    "rrgmrg" <[email protected]> wrote:

    >I am trying to choose between two stems for a new road bike that I am putting together (head tube
    >angle of 73.5 degrees). One stem is listed as -10 degrees (Deda), one as 80 degrees (ITM). I'm
    >confused. What's the difference ? Which one will result in higher/closer bars ? What stem angle
    >will result in a stem that is parallel to the ground, 16.5 ? How much does a 10 degree difference
    >affect the reach to the bars ?

    Others have chimed in on the confusing standards that are used to describe the same stem angle. To
    see the difference between two stems with extensions at different angles, check out my stem fit
    chart at http://www.habcycles.com/fitting.html

    It makes it very simple to calculate the difference in position between any two stems.

    Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame
     
  6. rrgmrg-<< One stem is listed as -10 degrees (Deda), one as 80 degrees (ITM). I'm confused. What's
    the difference ?

    Same angle.

    << What stem angle will result in a stem that is parallel to the ground,

    Neither-need a minus 17 degree stem.

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

    Rrgmrg Guest

    Sorry for seeming dense, I never did do well in geometry. Just want to make sure that I am
    understanding.

    A -10 (or 80) degree stem on a bike with a head tube angle of 73.5 will result in a stem that is
    angled UP 6.5 degrees (relative to being parallel to the ground) ?

    Similarly, a -6 degree stem (Easton) would result in a stem that is angled UP 10.5 degrees.

    Did I pass ?

    Thanks for your responses.

    Randy
     
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