Your aerodynamic efficiency, measured in CDA, depends on the interaction of individual pieces of equipment together with the rider’s position. This is because the flow around one object influences the flow around neighboring objects. For example, a different aerobar position might affect the aerodynamic performance of e.g. a helmet, and this result is likely different dependent upon head position. Similarly, the choice of wheel can affect the aerodynamic performance of a frame. This complexity offers many opportunities for improvement through aerodynamic testing.