Bicycle Power Calculator
Bicycle Power Calculator
Assumptions:
Constant speed analysis
Drag coefficients reference "Science of Cycling", E.R. Burke, Leisure Press, 1986, pg 126.
Inputs
Wheel Diameter (inches)
Crank Length (inches)
Desired Constant Speed (mph)
Rider's Weight (lbs)
Bicycle Weight (lbs)
% Grade (+ for uphill,- for downhill)
Mechanical Losses (3-5% is typical)
%
Gear Ratio (#Teeth Rear/Front)
1.00 (28/28) Slowest
.872 (34/39)
.718 (28/39)
.615 (24/39)
.512 (20/39)
.435 (17/39)
.359 (14/39)
.654 (34/52)
.538 (28/52)
.461 (24/52)
.385 (20/52)
.327 (17/52)
.269 (14/52)
.200 (11/55) Fastest
Air Resistance Coefficient (lbf*s^2/ft^2) = Cd*FrontalArea
(Cd*A =.0044)
Straight Arms (Cd*A =.004)
(Cd*A =.0036)
Full Crouch (Cd*A =.0032)
(Cd*A =.003)
Hill Descent (Cd*A =.0027)
No Rider (Cd*A=.0012)
Zero Air Drag (Cd*A=0)
Rolling Resistance Coefficient (lbf/lbf)
.013 (27x2.25" 45 psi BMX Knobby Tires)
.010
.007
.004 (27x1.125" 95 psi Road Clinchers Racing Tires)
0.00 (Zero Rolling Resistance)
Calculated Outputs
Total required input power from the rider
HP
Watts
Power needed to overcome air resistance
HP
%
Power to overcome rolling resistance in tires
HP
%
Power needed for elevation change
HP
%
Power lost to mechanical losses, friction, etc.
HP
%
Calories burned per mile
kcals (assuming 28% efficiency in conversion to human power output)
Average Pedal Force
Lbs Average Traction Force
Lbs
Pedal Speed
RPM Tire Speed
RPM
You are visitor #
since 14 March 2005
copyright 1999 Penn State
19 August 2005 by John S. Lamancusa - Penn State University (
jsl3@psu.edu
)
Accuracy checked by ME288 Product Dissection class,
Underlying Equations