Background: Research has found that manipulation of a single variable of bike-fit such as saddle height can improve performance within cycling efficiency (Peveler, & Green., 2010: Journal of Strength and Conditioning Research, 25(3), 1–5) and reduce aerodynamic drag (Garcia-Lopez et al., 2008: Journal of Sports Science, 26, 277-286). However, limited research exists concerning the biomechanical influences on gross efficiency, a key factor in endurance performance (Ettema, & Lorås., 2009: European journal of applied physiology, 106(1)1–14). In addition, many private companies offer numerous bike-fitting systems yet fail to provide consistent findings. The present study proposed to build on previous research by using a dynamic bike fitting system to explore how a number of biomechanical manipulations to a cyclist’s position can affect performance and cycling gross efficiency. Purpose: The main aim of the study was to investigate the effects on performance by manipulating a cyclist’s bike fit in-line with normative bike fitting data. For the purpose of this study the identifiable performance improvement was gross efficiency (GE) and the system that was used to perform the bike-fit was the Retül bike-fit system. The hypothesis tested was that changing a well-trained cyclist’s position in-line with normative data using a popular bike fitting system could improve performance in cycling gross efficiency. Method: Six well-trained cyclists (mean ±s: age, 30 ±13.1 years; height, 179.9 ±5.7 cm; mass, 75.1 ±8.1 kg; Wmax, 330 ±19.1 W; VO2 max, 66.1 ±10.3 mL.kg-1.min-1) completed one VO2max test, two sub maximal tests and one Retül bike fit. Submaximal tests consisted of three randomised 8 min incremental workloads of 50%, 60% and 70% VO2max. VO2 and VCO2 were recorded for final 4 min. The tests measured maximal minute power (Wmax), blood lactate, VO2max, VO2, VCO2 and GE. The data was analyzed using a Wilcoxon signed-rank test and a one tailed t- test. Results: Significant changes were observed (p=0.037) during the post bike-fit condition within the 60% Wmax increment (16.78% vs.17.44%; p= .037). Although non-significant, increases were apparent within the 50% Wmax increment (16.27% vs. 16.44%; p= 0.565) and again within the 70% Wmax workload (17.60% vs. 18.18%; p= 0.111). Discussion: The findings of the present study show higher % increases in GE than previous studies related to changes in GE over time (2.74% in the present study vs. 1-2% (Coyle, 1995: Exerc. Sport Sci. Rev. 23, 25–63). This suggests biomechanical changes can improve performance in well-trained cyclists. Further analysis shows a possible trend within cycling experience and GE improvements within the participant group that would benefit from further investigation. Conclusion: This study has found an increase in gross efficiency between pre and post bike-fit conditions. Specifically, one of the more noteworthy findings to emerge from this study is that at 60% Wmax GE was significantly increased across the participant group. Although the current study is based on a small sample of participants, the findings suggest that overall the absolute % increase in GE within each incremental workload would offer performance enhancements following improvements to their bike position.
Bateman, J. (2014). Influence of positional biomechanics on gross efficiency within cycling. Journal of Science and Cycling, 3(July), 2014.