All Vardena jerseys and bibs are completely handmade and designed in Italy following sophisticated engineering processes based on the most refined knowledge of fluid dynamics in order to maximize the athlete’s aerodynamics while on the saddle.
This way, Vardena garments maximize the ability of the athlete to penetrate the air while riding, a fundamental characteristic to save power when cycling and to reach higher speeds, since the aerodynamic resistance increases with the power to the square of the speed of advancement.
The aerodynamic resistance in cycling
The cyclist in movement inside a gaseous fluid is subject to a force called aerodynamic resistance. The “system” cyclist plus bicycle, whose perpendicular dimension to the motion of advancement is predominant compared to the others, falls into the cases of aerodynamics of bluff bodies. Substantially the cyclist going through the air exchanges with it some forces on the surface of separation between the fluid and the body due to the viscosity of the air. The result of all these exchanged forces is the aerodynamic resistance or drag, applied in a determined point called center of pressures. The entity of the aerodynamic resistance strongly depends on the speed of advancement of the cyclist and on the front surface directly exposed to the air, a variable that depends on the position taken in the saddle.
GENERATION OF THE SWIRLING TRAIL ZONES
The air, because of its viscosity, by passing the body of the cyclist, loses energy and through the mechanism of separation of the flow lines generates as its output what is called a recirculation zone.
In the boundary layer area in output, due to the lower passage section available, the speed of the separated flow will be greater and consequently its lower static pressure will be less than the corresponding upstream generating like this the whirling motion of the trail.
This pressure difference between upstream and downstream of the cyclist body generates the aerodynamic resistance to the point that in advancing a whirling trail is produced with negative pressure. As a matter of fact, the cyclist, by advancing through the air, generates a force that deters from the rear contrary to its motion due to the negative pressure in its trail.
The width of the trail depends on the point in which the fluid is detached from the body (separation point), the location of this point depends on the nature of the wall boundary layer (laminar or turbulent), which in turn depends on the surface’s finishing.
Especially with the increasing forward speed, it is important to maintain the wall boundary layer turbulent because this condition, in the bluff bodies, is capable of delaying the release of the fluid from the body, creating a smaller trail width and consequently a lower aerodynamic resistance.
Fundamental to ensure this nature of the boundary layer, and reduce the trail, is the targeted placement of the surface roughness of the materials in the various areas of the apparel.
Specifically, it is very important to have a “Patch-Work” construction of the clothing, where the roughest part is positioned where the first contact occurs between the uniform and the air.
A practical example of this type of aerodynamic solution is golf balls that having a series of dents on the surface, maintain the turbulent boundary layer flow, postponing the flow detachment in a very backward position of the ball surface, reducing the size of the rear trail and consequently the aerodynamic resistance, allowing the ball to travel a greater distance in flight.