Hello all,
I made a spreadsheet, using the cycling power equation to calculate the separate components of power given input of all the variables. There's some guesswork on the coefficients, but I think it's pretty easy to get reasonably close. The components of resistence are 1)aero, 2)rolling, 3)frictional, 4)gravitational, and 5)inertial, or acceleration.
Out of curiosity, I wanted to compare power requirements at my current weight to my ideal weight. Obviously, gravity is a component affected by weight, but acceleration is also. Even in a flat ride/race, like a crit, weight will increase power requirements because of the accelerations. Keep in mind that I'm about 35 lbs over where I want to be, so the power differences are real.
However, it's hard to nail down the effect of accelerations because they're so variable and frequent. Also, the accompanying decelerations slightly mitigate the effects. But I thought I'd like to try to get a rough guess using a very simple model without differential equations.
I assumed a 0.5 mile, 4-corner course, 4 accelerations of 5sec from 25 to 28 mph each lap. Power from accelerations equals mass*speed*acceleration. Energy during the accelerations would be mass*avg speed*delta speed. Adding the energy for all accelerations and dividing by total time gives the extra power. Using 100kg versus 80kg yields a difference of 18 W over an hour.
Decelerations complicate things because even in a very simple model, extra mass means less power needed during decelerations. So that 18 W difference would be reduced in my example to maybe about 10 W.
Of course it's very rough, but does this approach seem reasonable?
I made a spreadsheet, using the cycling power equation to calculate the separate components of power given input of all the variables. There's some guesswork on the coefficients, but I think it's pretty easy to get reasonably close. The components of resistence are 1)aero, 2)rolling, 3)frictional, 4)gravitational, and 5)inertial, or acceleration.
Out of curiosity, I wanted to compare power requirements at my current weight to my ideal weight. Obviously, gravity is a component affected by weight, but acceleration is also. Even in a flat ride/race, like a crit, weight will increase power requirements because of the accelerations. Keep in mind that I'm about 35 lbs over where I want to be, so the power differences are real.
However, it's hard to nail down the effect of accelerations because they're so variable and frequent. Also, the accompanying decelerations slightly mitigate the effects. But I thought I'd like to try to get a rough guess using a very simple model without differential equations.
I assumed a 0.5 mile, 4-corner course, 4 accelerations of 5sec from 25 to 28 mph each lap. Power from accelerations equals mass*speed*acceleration. Energy during the accelerations would be mass*avg speed*delta speed. Adding the energy for all accelerations and dividing by total time gives the extra power. Using 100kg versus 80kg yields a difference of 18 W over an hour.
Decelerations complicate things because even in a very simple model, extra mass means less power needed during decelerations. So that 18 W difference would be reduced in my example to maybe about 10 W.
Of course it's very rough, but does this approach seem reasonable?