Simplified deceleration method for assessment of resistive forces in cycling

Purpose: The purpose of this study was to develop and test a simplified dec eleration technique for measurement of aerodynamic and rolling resistances in cycling. Methods: Coast-down tests were performed in level hallways with an experienced cyclist as the rider. Average initial velocities were 2.5-1 2.8 m.s(-1). The deceleration technique was simplified by the use on only t hree switches and a derivation that did not require an assumption that dece leration is constant. The effective frontal area (AC,) and coefficient of r olling resistance (C-R) were then calculated through a derivation from the equation for resistive forces opposing motion. Method reproducibility was r ested by comparison of results for four tests of 30 trials under identical conditions. Method sensitivity was tested by performing 30 trials with thre e different rider head positions and four different transported mass condit ions. Results: Analysis of variance revealed that there were no differences among the results in the reproducibility study for either AC(D) or C-R. Fu rthermore, the reproducibility tests revealed mean errors of only 0.66% and 0.70% for AC(D) and C-R, respectively. ANOVA identified a significant incr ease (P < 0.001) in rolling resistance with external loading and a signific ant effect (P < 0.001) of head position on AC(D). Mean (+/-SD) values for A C(D) and C-R from tests in a racing aeroposture with the head up, the head in line with the trunk, and the head in an intermediate position were 0.304 +/- 0.011, 0.268 +/- 0.010, and 0.262 +/- 0.013 m(2), respectively; C-R av eraged 0.00368 in the three head positions. Conclusions: The findings indic ate that this simplified deceleration technique is satisfactorily reproduci ble and sensitive for measurement of aerodynamic and rolling resistances in cycling.