• Downforce spoilers provide smooth body streamline and downward force.
• In 1930s the fairings mounted into bike looked like a submarine and were named as “Dustbin Fairings” for smooth body streamline.
• In 1957, Moto Guzzi V8 integrated with “Dustbin Fairing” achieved a top speed of 273 kmph with just 78 hp which is 24 kmph less than the 2012 Hayabusa (top speed 297 kmph) which creates 197 hp.
• Air drag is calculated with the help of CdA value, the smaller the value the faster the bike is with same output performance. It is expressed in m2.
• Ducati introduced a new winglet design in 2015 by implementing it in their bike. FIM banned it in 2016.
• Danny Aldrich, technical director of MotoGP approved that the winglets are safe and are no concern for safety.
Just like car spoilers, bike downforce spoilers or winglets are mounted for the same very purpose for the bike, to provide a smooth body streamline as well as a downward force. Today every racing sports bike manufacturers like Panigale V4 Superleggera, BMW S1000RR, Aprilia RSV4 RF and many more are making their bike integrated with winglets for better aerodynamic effect including downforce. But surprisingly these were once misunderstood and were even banned for using.
Since 1920, aerodynamics for motorbike were always a topic of concern and even today scientists are doing continuous research and experiments to reduce the air drag. During 1930s many bike manufacturers were experimenting with bike fairings, they give it a submarine looking shape referred to as “dustbin fairings”. It was found that the top speed of the bike could be increased without any additional power. In 1957, the Moto Guzzi V8 integrated with dustbin fairing, achieved a top speed of 273 km/h at the Mirror Test Track and 286 km/h at Belgian GP. Surprisingly the bike produced 78 hp and weighs 148 kg only. Comparing to it, Suzuki Hayabusa of 2012 which is 264 kg in weight produce 197 hp, achieves top speed of 297 kmph, only 24 kmph faster than the 1950s Guzzi. This is because of the dustbin fairing in Guzzi which reduces the air drag.
Air drag can be calculated with the CdA value, it is a combined drag coefficient and reference area, it refers to the wind resistance and aerodynamic of the bike. It is expressed in m2. The smaller the value the faster the ride in same output performance. Guzzi has a CdA value of 0.186 m2 and that of Hayabusa is 0.27 m2. So we can conclude how effective is the CdA value on top speed. Despite of covering the whole rider which is the main cause of turbulent flow in air streamline increasing the CdA value, in 1958 the FIM banned the dustbin fairing because the center of pressure was ahead of the center of gravity making it unstable during races.
Manufacturers now focuses on decreasing the turbulence around the rider by taking ideas from aerospace industries like winglets and vortex generators. In 2015 during the Moto GP racing Ducati introduced a new winglet design by implementing it in their fairings, it made the bike anti-wheelie at high speeds and give the rider a grip on front tyre.
But many riders had safety concerns about the winglets and later FIM banned it and later it was known as “The Winglet Ban”. It was proven wrong in 2018 Sepang Testing by Danny Aldrich the technical director of MotoGp that the updated winglets are no more safey concern for the rider. Winglets are now seen in almost every racing sports bike, but as the technology is continuously changing we could find more advanced and safe wind resistance in future bikes.