Power to Speed
A simple calculator. Flat course, no wind, 20°C...
Weight of rider + bike = kg
CdA = 0. m2
Power = Watt
About this calculator
Because the speed of a cyclist depends on many factors, the above calculator will only give you a rough idea of the power to speed ratio in terms of the aerodynamic drag coefficient CdA. In order to do so the calculator has to make a few assumptions. To name a few: A flat course, a cyclist riding an average road/triathlon bike equipped with Continental Grand Prix 4000 S II tires and an air density which you often experience at 20°C and close to the sea level.
The drag coefficient CdA
It is not entirely correct to name the CdA value "drag coefficient", since the CdA is the product of the real drag coefficient cd (often also named cw) and A - the frontal area of rider and bike. The CdA of a road cyclist, riding with his hands on the hoods can be around 0.4 m2, while the best time trialists and triathletes achieve CdAs as low as 0.2 m2. Of course, the body size, the material and above all the riding position play an important role here, so that the value varies for every athlete and every bike.