Power, CdA and Velocity Calculator

Being able to quantify your aerodynamic efficiency is hugely valuable when searching for performance gains.

The data allows you to compare the effects of power output, riding velocity and your CdA against one anther to determine on the bike performances. From here, you can then make informed decisions and to steer your setup choices or race tactics. 

This calculator allows you to determine an output variable between Power, CdA and constant Velocity based on inputting two inputs. 

For example, you can determine your CdA based on power and speed, then use this CdA to determine how much power is required to ride at a certain speed etc.

Constraints are adjustable for advanced users such as your rolling resistance, rider/system weight, mechanical efficiency and air density to further refine the results.

  

Advanced Constraints

Rolling Resistance (Crr): More information on specific tyres can be found on resources such as Bicycle Rolling Resistance.

0.002 - 0.003 = Indoor wooden velodrome
0.003 - 0.004 = Smooth concrete velodrome
0.004 - 0.005 = Asphalt (Bitumen) surface

Weight (Kg): The weight of the whole rider / bike system (including rider, bike, shoes, helmet, etc.)

Mechanical Efficiency: Can is difficult to measure. If unknown, make the following assumptions for track bikes:

0.94 = Poorly maintained drive chain (or a standard road bike drive chain)
0.96 = Competitive but not fully optimized
0.98 = World class components, quality performance bearings etc.

Air Density: If access to a air density meter such as a Kestrel Environment Meter, this live data can be used. If air density is unknown, assume 1.225 kg/m3 (15° at sea level).

 

What does a good CdA look like?

These ranges are rough estimates of what you would expect to see from competitive amateurs through to world class athletes.

0.30 - 0.35 = Road bike training
0.24 - 0.32 = Road racing
0.19 - 0.26 = Bunch and sprint track racing
0.18 - 0.25 = Time trial/triathlon
0.17 - 0.24 = Pursuit track racing
0.15 = Most slippery and optimised bike and rider currently known

 

Visit our Aero Testing Process Guide for more information on testing and validating your CdA data.

© Velobike Innovation Limited

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