This cycling wattage calculator is a tool designed for all cycling passionates. With its help, you can explore the relationship between the power you produce and various parameters such as speed, biking position, hill slope, or pavement type. For example, you can find out how much power you can save when switching from knobby to slick tires.
Thanks to this cycling power calculator, you will finally be able to compare two cyclists with fundamentally different styles - for example, a road cyclist who never gets off his slick-tired bike, and an MTB-enthusiast who enjoys hardcore off-road adventures.
Cycling wattage is the power you produce with your legs to get your bike going (and, preferably, going fast). You can think of it as the ultimate measure of your biking skills: the more power you can produce, the better cyclist you are.
The cycling power is measured in Watts. One Watt corresponds to one Joule of energy produced every second.
Our cycling wattage calculator is based on the model described in detail in the paper "What is slowing me down? Estimation of rolling resistances during cycling". It assumes that the power you produce is equal to the sum of resistances you need to overcome, multiplied by your speed. Additionally, we take power losses into consideration.
The cycling wattage formula that we use looks like this:
P = (Fg + Fr + Fa) * v / (1 - loss)
In the next sections of this text, we will look at each component of this cycling power equation in more detail.
If you're cycling uphill, you need to overcome the force of gravity. Naturally, if you're going downhill, the gravity will actually help you, making you accelerate without any additional effort.
The force of gravity can be calculated as
Fg = g * sin(arctan(slope)) * (M + m)
The next factor that will undoubtedly slow you down is the friction between your tires and the surface. The smoother the road and the slicker your tires, the less friction you will experience.
The formula for rolling resistance is
Fr = g * cos(arctan(slope)) * (M + m) * Crr
The estimates for the rolling resistance coefficient Crr in our cycling wattage calculator are based on the findings of researchers from the University of Pretoria and the University of Reims Champagne Ardenne:
|surface type||slick tires||knobby tires|
The third component of the power equation is the aerodynamic drag. It's a force of air resistance. Unlike the previous two components, it's dependent on your speed raised to the second power - the faster you are, the higher the air resistance. It means that the faster you go, the more difficult it is to keep speeding up.
The aerodynamic drag can be calculated according to the formula below:
Fa = 0.5 * Cd * A * ρ * (v + w)²
It is common to estimate the value of Cd * A instead of determining each of these two separately. We are using the values suggested by Asker E. Jeukendrup in his book "High Performance Cycling":
|position||Cd * A|
The positions are:
Additionally, our cycling wattage calculator estimates the air density on a given elevation above sea level according to the barometric formula:
ρ = ρₒ * exp[(-g * Mₒ * h) / (R * Tₒ)]
After substituting the constants, this equation can be simplified to
ρ = 1.225 * exp(-0.00011856 * h)
Not all of the power that you produce when cycling is transferred directly to the wheels. Some of it is lost either due to the resistance of the chain or of the derailleur pulleys.
Our cycling power calculator assumes a constant 1.5% loss on your pulleys. The losses on the chain are dependent on its condition:
You can check out this article on mechanical resistance of bikes for more information about the power losses.
Now you know your cycling wattage - but what does that number mean, exactly? The table below provides with an overview of the power-to-weight ratio (power that can be produced per kilogram of body weight) compiled by Dr. Andrew Coggan, a renown exercise physiologist.
|cyclist type||5 minutes||20 minutes||1 hour|