THE INFLUENCE OF BODY-MASS IN ENDURANCE BICYCLING

Bicycling is a complex sport in which an athlete's energy cost is rela ted to two principal forces: air resistance when traveling on flat ter rain, and gravity when traveling uphill. Both wind tunnel data and phy siological measurements suggest that air resistance scales as body mas s to about the 1/3 power. Thus, large cyclists have only slightly grea ter frontal drags than small cyclists. if expressed relative to body m ass, the frontal drag of small cyclists is considerably greater than t hat of large cyclists. The difference in frontal drag (energy cost) is not made up for by the advantage to small cyclists in relative VO2max , (energy supply), since the mass exponent for drag (1/3) is closer to zero than that for VO2max (2/3). Thus, small cyclists should be at a disadvantage in flat time trials, which field data support. The energy cost of riding uphill slightly favors the large cyclist, because the weight of the bicycle represents a relatively smaller load than it doe s to a small cyclist. The mass exponent is 0.79. Since this exponent i s greater than that for VO2max, the small cyclists have an advantage i n climbing, which is supported by field data.