The frontal wind has to ‘pass around’ the tubes of the bike, and has to change its direction to follow the profile of the bike. To make it easier for the airstream to follow the profile of the bike and stay close to the bike, the tubes are designed in a droplet shape.
However, even then it’s not possible to keep the airstream in touch with the frame at every location. At certain locations the airstream releases the frame, creating a wake on these locations which increases the drag. Therefore we did extensive wind tunnel testing and used oil mapping technology to locate the places where the wind releases the frame. To avoid the airstream releasing from the frame on these locations, we apply a structure surface on well defined locations in order keep to the wind close to the frame. This reduces drag, optimizing the speed a bike can obtain once again.
For more information check: www.fast-concept.com