In this study, the oxygen consumption (VO2) of bicycling was measured at a fixed speed (40 km.h-1), on level terrain, with normal and aerodynamic handlebars using a Douglas bag collection system. Eleven elite (USCF category 1 or 2) men cyclists age 24 to 40 years (mean = 28.5, SD +/- 4.6) performed four consecutive (two with each bar in alternating order) steady state rides at 40 km.h-1 over a 4 km flat course (same direction each trial). Expired gases were collected in a 1501 Douglas bag attached to a following vehicle during the last 45 s (approx. 0.5 km) of each trial. A repeated measures analysis of variance revealed a significant (p < 0.02) handlebar effect. Specifically, VO2 was 2% lower under the aerodynamic handlebar treatment (mean = 4.26, SD +/- 0.36 l.min-1) when compared with that of the normal handlebar treatment (mean = 4.34, SD +/- 0.35 l.min-1). The results of this study demonstrate that the reported aerodynamic advantage of the aerodynamic handlebars produces a small but significant reduction in the VO2 of bicycling at 40 km.h-1.