Field-measured drag area is a key correlate of level cycling time trial performance

Drag area (A(d)) is a primary factor determining aerodynamic resistance during level cycling and is therefore a key determinant of level time trial performance. However, A(d) has traditionally been difficult to measure. Our purpose was to determine the value of adding field-measured A(d) as a correlate of level cycling time trial performance. In the field, 19 male cyclists performed a level (22.1 km) time trial. Separately, field-determined A(d) and rolling resistance were calculated for subjects along with projected frontal area assessed directly (A(P)) and indirectly (Est A(P)). Also, a graded exercise test was performed to determine [Image: see text] peak, lactate threshold (LT), and economy. [Image: see text] peak ([Image: see text] ) and power at LT were significantly correlated to power measured during the time trial (r = 0.83 and 0.69, respectively) but were not significantly correlated to performance time (r = − 0.42 and −0.45). The correlation with performance time improved significantly (p < 0.05) when these variables were normalized to A(d). Of note, A(d) alone was better correlated to performance time (r = 0.85, p < 0.001) than any combination of non-normalized physiological measure. The best correlate with performance time was field-measured power output during the time trial normalized to A(d) (r = − 0.92). A(P) only accounted for 54% of the variability in A(d). Accordingly, the correlation to performance time was significantly lower using power normalized to A(P) (r = − 0.75) or Est A(P) (r = − 0.71). In conclusion, unless normalized to A(d), level time trial performance in the field was not highly correlated to common laboratory measures. Furthermore, our field-measured A(d) is easy to determine and was the single best predictor of level time trial performance.