With existing wheel manufacturers who place their design focus on the leading edge of the leading section of the bicycle wheel, their rim designs evolved into end-to-end symmetrical airfoil shapes which became known as Toroidal or U-shaped rims. This will explain why so many carbon bicycle wheel manufacturers also had to incorporate the influence of the tire on the rim’s airfoil design and in some cases also started to design their own tires due to the strong influence of the tire on this design approach.
Although we agree that these symmetrical airfoil shapes do have its advantages and should not be ignored, our research also found that we were able to gain a far greater aerodynamic benefit from reducing more drag from the bicycle frame and from the cyclist’s pedaling motion with the optimization of the airfoil profile of the rim at the trailing section of the front wheel.
With the Zagon Trailing Airflow Optimization (ZTAO™) design approach in combination with Computational Fluid Dynamics (CFD), we were able to engineer a rim airfoil profile that starts with a fairly sharp parabolic contour (in comparison to traditional U-shaped profiles) at the spoke bed area which then gradually widens further towards the brake track of the rim. This allows for the widening of the airflow to create a larger low-pressure area where the airflow passes the tire, bicycle frame and the rotational pedaling motion from the cyclist. This significantly minimized the impact the airflow drag force has on the integrated Bicycle as a System (BaaS™), in comparison to currently shaped carbon airfoil shapes.