Rise and Fall of Winglets in MotoGP
MotoGP is the pinnacle of motorcycle racing, just like Formula 1 is to car racing, so it should come as no surprise that aerodynamics is a key element for success. The focus in MotoGP was on drag reduction through streamlined fairings, helmets, and outfits. Then in 2015 Ducati added winglets to their front fairings to produce downforce.
At first glance adding downforce to a motorbike seems a strange move when you see the extreme lean angles riders use for cornering. In such cases it would seem downforce would make the leaning unstable. However, the winglets Ducati added (quickly followed by other manufacturers) were not for cornering speed (as in Formula 1), they were for acceleration.
During full throttle acceleration the front wheel on the MotoGP bikes literally lifts off the ground. Up until the addition of winglets, strategies to manage front wheel lift (wheelie) had been deployed typically through some form of engine power reduction (e.g., electronic throttle control). With these approaches reduced power meant reduced acceleration and therefore reduced performance. With the production of downforce via the winglets the bikes could use a wider range of engine power without the front wheel lifting, and thus realize more of the performance available from the engine.
As with many aerodynamic innovations in sports the governing body often takes a hard initial line and so it was with winglets in MotoGP. For the 2017 MotoGP season winglets are banned, citing rider safety during crashes as the driver for the ban.