Decrease Seat to Bars Vertical Distance (Trig Check)

Discussion in 'Cycling Equipment' started by Tom S, Aug 24, 2003.

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  1. Tom S

    Tom S Guest

    My bars are about 1 inch too low for my preference and I want to decrease the vertical distance.
    (OK, I'll admit I'm getting older and have lost some suppleness.) In order to save time on
    installing and removing (possibly) numerous stems, I thought I'd try to remember some high school
    trig. Here was my approach: My current stem is installed with a 7 degrees up angle, 130mm (5.2 in
    length). If I install a new 17 degree stem with the same 130mm length, the rise towards the bars of
    the stem should be 0.95 inches. TAN(&)= y/x; x=5.2 in

    Did I commit any glaring errors in the thought process?
    --
    Tom S
     
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  2. Can't help with the trig, but if the angle of the stem increases and the length stays the same, not
    only will the bars come up, but they will also come closer. So if you want the same overall reach
    you will have to get a longer stem.

    "Tom S" <[email protected]> wrote in message
    news:[email protected]...
    > My bars are about 1 inch too low for my preference and I want to decrease the vertical distance.
    > (OK, I'll admit I'm getting older and have lost
    some
    > suppleness.) In order to save time on installing and removing (possibly) numerous stems, I
    > thought I'd try to remember some high school trig. Here was my approach: My current stem is
    > installed with a 7 degrees up angle, 130mm (5.2 in length). If I install a new 17 degree stem
    > with the same 130mm length,
    the
    > rise towards the bars of the stem should be 0.95 inches. TAN(&)= y/x; x=5.2 in
    >
    > Did I commit any glaring errors in the thought process?
    > --
    > Tom S
     
  3. Mark Hickey

    Mark Hickey Guest

    "Tom S" <[email protected]> wrote:

    >My bars are about 1 inch too low for my preference and I want to decrease the vertical distance.
    >(OK, I'll admit I'm getting older and have lost some suppleness.) In order to save time on
    >installing and removing (possibly) numerous stems, I thought I'd try to remember some high school
    >trig. Here was my approach: My current stem is installed with a 7 degrees up angle, 130mm (5.2 in
    >length). If I install a new 17 degree stem with the same 130mm length, the rise towards the bars of
    >the stem should be 0.95 inches. TAN(&)= y/x; x=5.2 in
    >
    >Did I commit any glaring errors in the thought process?

    It's too late to do trig. Save yourself some time:

    http://www.habcycles.com/fitting.html

    Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame
     
  4. Grenouil

    Grenouil Guest

    "Tom S" <[email protected]> wrote in message
    news:[email protected]...
    > My bars are about 1 inch too low for my preference and I
    want to decrease
    > the vertical distance. (OK, I'll admit I'm getting older
    and have lost some
    > suppleness.) In order to save time on installing and
    removing (possibly)
    > numerous stems, I thought I'd try to remember some high
    school trig. Here
    > was my approach: My current stem is installed with a 7 degrees up angle,
    130mm (5.2 in
    > length). If I install a new 17 degree stem with the same
    130mm length, the
    > rise towards the bars of the stem should be 0.95 inches.
    TAN(&)= y/x;
    > x=5.2 in
    >
    > Did I commit any glaring errors in the thought process?
    > --
    > Tom S
    >
    >
    To be picky, if you want vertical distance you need a sine function, not tangent. A 13cm stem angled
    7 degrees up from the horizontal will put the bars 0.1219*13 = 1.58cm above the horizontal. A 13cm
    stem angled 17 degrees will put the bars 0.2924*13 = 3.80cm above, for an increase of
    2.22cm......

    That said, there's not a hell of a lot of difference between sine and tangent for small angles -
    tan(17) is 0.3057 - so you're close enough.....

    As someone else pointed out, the bars will also move closer to the seat - use the difference in the
    cosines of the two angles multiplied by the stem length to calculate how much closer
     
  5. Tom S <[email protected]> wrote:

    > My bars are about 1 inch too low for my preference and I want to decrease the vertical distance.
    > (OK, I'll admit I'm getting older and have lost some suppleness.) In order to save time on
    > installing and removing (possibly) numerous stems, I thought I'd try to remember some high school
    > trig. Here was my approach: My current stem is installed with a 7 degrees up angle, 130mm (5.2 in
    > length). If I install a new 17 degree stem with the same 130mm length, the rise towards the bars
    > of the stem should be 0.95 inches. TAN(&)= y/x; x=5.2 in

    Your calculations are most likely correct, if the angles you mention are relative to the horizontal
    plane. If you buy a stem that is marketed as +- 6 degrees, for example, it means that the rise with
    a 72 degree head tube is actually 24 (18+6) or 12 degrees (18-6). Also, as was mentioned, a stem of
    the same length at a higher angle brings the handlebar slightly closer also horizontally.

    -as
     
  6. Tom

    Tom Guest

    From one Tom to another one. I'm 73, try a $19.95 3" stem extender and then you can get the height
    you want and stay with the same stem. It worked for me. Old age is tough; but, the alternative is
    worse. Keep riding.

    Tom

    -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1
    Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =-----
     
  7. Sorni

    Sorni Guest

    "Grenouil" <[email protected]> wrote in message
    news:[email protected]...

    > To be picky, if you want vertical distance you need a sine function, not tangent. A 13cm stem
    > angled 7 degrees up from the horizontal will put the bars 0.1219*13 = 1.58cm above the horizontal.
    > A 13cm stem angled 17 degrees will put the bars 0.2924*13 = 3.80cm above, for an increase of
    > 2.22cm......
    >
    > That said, there's not a hell of a lot of difference between sine and tangent for small angles -
    > tan(17) is 0.3057 - so you're close enough.....
    >
    > As someone else pointed out, the bars will also move closer to the seat - use the difference in
    > the cosines of the two angles multiplied by the stem length to calculate how much closer

    Or, eyeball it.

    :)

    Bill "rotate dem risers" S.
     
  8. Tom S

    Tom S Guest

    Thanks to all responders, greatly appreciated. New stem on the way.

    Tom

    --
    Tom S "Tom S" <[email protected]> wrote in message
    news:[email protected]...
    > My bars are about 1 inch too low for my preference and I want to decrease the vertical distance.
    > (OK, I'll admit I'm getting older and have lost
    some
    > suppleness.) In order to save time on installing and removing (possibly) numerous stems, I
    > thought I'd try to remember some high school trig. Here was my approach: My current stem is
    > installed with a 7 degrees up angle, 130mm (5.2 in length). If I install a new 17 degree stem
    > with the same 130mm length,
    the
    > rise towards the bars of the stem should be 0.95 inches. TAN(&)= y/x; x=5.2 in
    >
    > Did I commit any glaring errors in the thought process?
    > --
    > Tom S
     
  9. x

    x Guest

    RE/
    >Old age is tough

    "Old age is not for sissies..."
    -----------------------
    PeteCresswell
     
  10. x

    x Guest

    RE/
    >Anybody that says "I'm not gettin older, I'm getting better", I think I want to punch them.

    And there were people like Jacques Cousteau who maintained that they didn't feel any different at,
    say, 65 than they did at 20. I remember when I heard that thinking "Jacques, baby, you've been
    laying around on that boat too much all these years. If you'd been pushing any kind of envelope,
    you'd sures notice the diff..."
    -----------------------
    PeteCresswell
     
  11. Damn! I left my machinery handbook and trig tables at work!!

    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
     
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