Effect of Bicycle Seat Tube Angle on Physiological and Kinematic Variables

Abstract

Amateur triathlon and time trial competition is a popular athletic activity in the United States. Anecdotal reports have indicated that there is an optimal bicycle seat tube angle (STA) for these events. However to date research has failed to confirm these reports. PURPOSE: To determine the physiological effects of riding 72° and 78° STA bicycles a) on physiological values while cycling at a constant resistance submaximal workload and b) VO2peak and power output at VO2peak. METHODS: Eight male cyclists/triathletes (Age 35.5 +/− 9.7 yrs, Height 180.0 +/−4.8 cm, Weight 74.5 +/− 5.9 kg, % body fat 11.6 +/− 2.5 %, VO2peak75degrees 4.5, +/− .4 L min−1, Cycling mileage 285, +/− = 94 km/week−1) performed a VO2peak test at on a bicycle with a STA of 75°. Seventy five percent of the workload achieved during the 75° VO2peak test was used as a workload for two constant resistance tests at STA of 72° and 78°. Subjects also completed VO2peak tests while riding at 72° and 78° STA. All tests were separated by at least 48 hours, and all 72° and 78° tests were randomized. For all tests VO2, VCO2, RER and VE and heart rate (HR) were measured. In addition pre and post lactate (La) values were measured during the constant resistance trials. RESULTS: Statistical tests used were dependent t-tests and Pearson product-moment correlations. No significant differences were found between the physiological variables measured during the 72° and 78° constant resistance tests. In addition there were no significant differences in the physiological measures between the 72° and 78° VO2peak tests. CONCLUSIONS: This study was conducted in a controlled laboratory setting. Although there were no significant differences in any of the physiological variables measured it is possible that the differences in STA were not great enough to see statistically significant differences. Furthermore field studies might be able to determine the optimal STA for time trial and triathlon performance.