The Pedaling Model can be used to
test the effects of changes in position, crank length, and shin length (heel
up or down can effectively change "shin length"). It can be used
to test the effects of different pedaling techniques and stronger muscle
development. How do longer cranks change power output? How is power affected
by changing seat position? Do people with shorter shins have an advantage?
Different regions within the full range of muscle motion could yield different
power outputs.
The Pedaling Model is more fully described at How Pedaling Model Works. See Figure
1 below for nomenclature.
Input Form
Thigh Length is the distance
in centimeters from the point of rotation at hip to point of rotation of
knee. Shin Length is the distance in centimeters
from the point of rotation of knee to center of pedal spindle. Hip's
Horizontal Distance is the horizontal distance
from vertical line through bottom bracket to point of rotation of hip. Rear
direction, positive, forward negative.
Pedal Model Points is the number
of divisions of a complete rotation of the pedals used in the model.
A value of 12 gives good results for most cases. However, if the torque
at the bottom bracket is all in a small portion of the pedal rotation, a
larger value will give better results.
A graphic is produced that shows geometric relationships,
torques from the shin and thigh, and forces at the pedals. Each of
the positioned modeled by Pedal Model Plot points can be chosen as
a position modeled by the graphic. Plot Position is
the position to be plotted and can be any positive integer less than or
equal to Pedal Model Points. The first position is one position
clockwise from top.
Thigh and Shin Extensor and Flexor Fit Points
are lists of points that the Pedal Model uses to define the
Thigh and Shin Extensor and Flexor strength functions. Such lists should
be values spaced evenly over a range of motion and are in units of N
m.
Fit Points Example:
{0., 88., 200., 232., 240., 232., 200., 88., 0.}
 The list begins and ends with "curly braces, {}"
 Each value must be separated by a comma.
 The model requires at least four points.
 Values can be zero; a "zero valued moment function."
is {0,0,0,0}.
A number in front of the list has the effect of multiplying
all the values in the list by this number, i.e., 2 {0., 88., 200., 232.,
240., 232., 200., 88., 0.} would give the same result as {0.,166.,400.,464.,480.,464.,400.,164.,0.}.
Sample Output
Values calculated by the Pedal Model, the input values
used for Fit Points, and a graphic are shown below. The graphic shows
the geometry, shin and thigh torques, and forces at the pedals at one position
of a pedal rotation are shown below.
.
Pedaling Model Output
Length of Thigh 
56.0 
cm 
Length of Shin 
44.5 
cm 
Length of Crank 
170. 
mm 
Point of rotation of thigh at hip 
{ 30.0, 76.0} 
cm 
Work of Revolution, one leg, 
155.9 
kg m^{2}/s^{2</ sup>} 
Work of back half of revolution, one leg, 
29.3 
kg m^{2}/s^{2</ sup>} 
Cadence 
100. 
rev/min 
Watts for two legs 
519.7 
kg m^{2}/s^{3</ sup>} 
Average pedal force for Watts 
291.9 
kg m/s^{2} 
Minimum angle between shin and thigh, Theta5Min 
22. 
degrees 
Maximum angle between shin and thigh, Theta5Max 
101. 
degrees 
Range of angle between shin and thigh, Theta5Delta 
79. 
degrees 
Minimum angle between thigh and horizontal,Theta2Min 
20. 
degrees 
Maximum angle between thigh and horizontal, Theta2Max 
60. 
degrees 
Range of angle between thigh and horizontal, Theta2Delta 
41. 
degrees 
Angle of hips, Theta8 
82. 
degrees 
Pedaling Model Fit Points
Hip Extensor Fit Points 
{ 0.0, 88.0, 200.0, 232.0, 240.0, 232.0, 200.0, 88.0, 0.0} 
Hip Flexor Fit Points 
{ 0.0, 12.5, 28.3, 32.9, 34.0, 32.9, 28.3, 12.5, 0.0} 
Shin Extensor Fit Points 
{ 0.0, 12.1, 27.5, 31.9, 33.0, 31.9, 27.5, 12.1, 0.0} 
Shin Flexor Fit Points 
{ 0.0, 7.7, 17.5, 20.3, 21.0, 20.3, 17.5, 7.7, 0.0} 
