Watch a modern MotoGP, Moto2 or World Superbike race with a casual fan and you can be certain there is one question they will ask you: “Why are they waving their legs about like that?” Many theories have been offered, often directly contradicting each other.

For example, several years ago, I suggested that the leg wave is entirely mental. Earlier this year, the Australian motorcycle coaching organization MotoDNA described the possible role which aerodynamics play, the exposed leg helping to create more drag. Much has been said, yet it seems impossible to settle the argument one way or another.

Asking the riders to explain does not help much. It is a question I and other journalists have asked of many different riders, including Valentino Rossi, Casey Stoner, Cal Crutchlow, and Dani Pedrosa. Their answers always boil down to the same thing: “It just feels natural,” they say. An interesting response, perhaps providing an insight into how deeply racers have internalized so much of the physical part of their riding, but not doing much to help explain the phenomenon.

To attempt to get to the bottom of this mystery, I turned to some of the best minds in the MotoGP paddock. For an explanation of the physics behind the leg wave, I asked Monster Tech 3 Yamaha crew chief and technical guru Guy Coulon, while for further insight from the point of view of an observer and ex-rider, I spoke to Wilco Zeelenberg, team manager of Jorge Lorenzo – the one current MotoGP rider who does not dangle his leg while riding.