Bicycle Power Calculator

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Assumptions:
Constant speed analysis
Bike weight = 22 lb
Drag coefficients reference "Science of Cycling", E.R. Burke, Leisure Press, 1986, pg 126.

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Inputs
Wheel Diameter (inches)        Crank Length (inches)
Desired Constant Speed (mph)       Rider's 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) Straight Arms (Cd*A =.004) Full Crouch (Cd*A =.0032) 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)

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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
    Average Pedal Force Lbs     Average Traction Force Lbs
    Pedal Speed RPM                Tire Speed RPM

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1 June 1999 by John S. Lamancusa - Penn State University (jsl3@psu.edu)
Accuracy checked by ME288 Product Dissection class
Modified to work with Netscape 4.0 by Matt Lindenberg