Biking Techniques (Part 11)

Aerodynamics

Basic Principles

Unlike most racecars, a bike is a brick. Having the rider stick out in the airflow, and not being able to fair in the front wheel, leaves a lot to be desired for aerodynamic efficiency. The bike tries to make up for it with power and low weight, but that only goes so far. To push the top end of speed and acceleration, the bike needs some help from the rider.

Aerodynamic drag increases with the square of the speed. Double the speed, and you get four times the drag. What that means in practical terms is that around 120mph, bikes run into what feels like a brick wall of air, and increasing your speed only a little needs a phenomenal amount of power. It also means that any difference the rider can make to drag will be multiplied and give big benefits. Even faired bikes are designed around a rider. The bike itself needs the rider in the right place to smooth the airflow.

From TrackDoD Novice Group Orientation