How works the calculators
Modify the value in one of the boxes, and use the 'tab' key to move the
focus to another box. Depending which thing you just modified, some of
the other things will be updated.
The things you expected to be updated might not be the only things that
get updated, so consider all of the new values that appear. Changing
different things updates different things, so you might need to do things
in a different order than you expected. Like I said, subtle and
mysterious ways...
Terminology
Most of this will be pretty clear to anyone who knows enough about
design to even find these things interesting, but just in case...
Running Length : also called "effective edge," this is the
amount of edge that actually contacts the snow. Think "board length minus
tip and tail."
Edge Angle : The angle between the board and the snow.
Decamber : The amount that the snowboard must flex in order to
keep the edge in contact with the snow. When the edge angle is zero,
decamber and camber are the same. As the edge angle increases, decamber
increases with it.
Effective Depth : When the board is flexed, the waist of the
board is further away from the tip-to-tail baseline than when the board is
straight. This 'effective' depth, coupled with the running length,
determines the carving radius. (However, note that "sidecut_radius *
cosine of edge_angle" yields the same results!).
Carve Radius : This is the radius of the path that the
snowboard will trace in the snow.
Inclination : Visualize a line from the edge of the snowboard
through the rider's center of mass. Inclination is the angle between this
line and the surface of the snow.
Angulation : The use of the rider's body to change the angle
between the snowboard and the imaginary line running from the edge through
the rider's center of mass. "Zero angulation" means that this imaginary
line is perpendicular to the snowboard.
Speed (assuming zero angulation) : This is the speed at which
centrifugal force and gravity keep the rider balanced at the given edge
angle. For comparison, 10 meters per second is equal to 22.5 miles per
hour. In practice, of course, the rider can use angulation to balance at
different speeds and carve radii.
Credits
Thanks most of all to Fin of bomberonline.com for creating a
place for hardbooting snowboarders to hang out and talk shop. Then thanks
to B. Mahoney for starting a thread on sidecut math. Then, thanks to Jack
Michaud for pointing out that that running length doesn't change the carve
radius if the sidecut radius is constant (I created this page out of
skepticism, but it only proved him right!), and also for providing the
math that calculates speed as a function of edge angle and sidecut radius.
Then, thanks to Rob Starr for putting forward some ideas about speed and
angulation that got me thinking.
JavaScript Source Code
Click
here for the snowboard calculator
Click
here for the angulation calculator
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