Created
October 18, 2013 14:21
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How much power in watts do you need on a stationary bicycle in order to replicate outdoor riding conditions given your weight, speed, wind resistance, and grade?
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| #http://en.wikipedia.org/wiki/Bicycle_performance#Aerodynamics_vs_power | |
| G = 9.8 #earth's gravitational constant | |
| K1 = 0.0053 #lumped constant for all frictional losses (tires, bearings, chain), and is generally reported with a value of 0.0053 | |
| K2 = 0.185 #lumped constant for aerodynamic drag and is generally reported with a value of 0.185 kg/m | |
| def power(velocity_ground, velocity_air, grade, mass): | |
| """ | |
| mass is in kg | |
| velocity_ground and velocity_air are in meters per second | |
| grade is percent eg 0.05, 0.12 | |
| """ | |
| return G*mass*velocity_ground*(K1+grade)+K2*velocity_air**2*velocity_ground | |
| def kg(pounds): | |
| return pounds*0.453592 | |
| def meters_per_second(miles_per_hour): | |
| return miles_per_hour*0.44704 | |
| def epower(velocity_ground, velocity_air, grade, weight): | |
| """ | |
| mass is in lbs | |
| velocity_ground and velocity_air are in miles per hour | |
| grade is percent eg 0.05, 0.12 | |
| """ | |
| velocity_ground=meters_per_second(velocity_ground) | |
| velocity_air=meters_per_second(velocity_air) | |
| mass=kg(weight) | |
| return power(velocity_ground, velocity_air, grade, mass) |
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