Advanced Analysis of Athlete Signals and Data: Optimization of Cycling Performance through a New Telemetry System for the Study of Tire Inflation Pressure

Pablo Díez-Martínez¹; Víctor José Barneto-Magen²; Antonio Cartón-Llorente¹; Alejandro Molina-Molina¹; Diego Jaen-Carrillo³; Alberto Roso-Moliner¹; Carlos García-Cebadera Gómez¹; Javier Fontan-Puig¹. 

Affiliations: ¹ Facultad de Ciencias de la Salud, Universidad San Jorge, Villanueva de Gállego, 50830 Zaragoza, España. ² Escuela de Arquitectura y Tecnología, Universidad San Jorge, Villanueva de Gállego, 50830 Zaragoza, España. ³ Department of Sport Science, University of Innsbruck, 6020 Innsbruck, Austria. 

Introduction 

In cycling, the analysis of the forces acting on the cyclist-bicycle system [CBS] is key to optimizing performance (1). Rolling resistance [RRF] is one of these forces, influenced by various factors, including tire inflation pressure (2). This study describes the development and implementation of a low-cost telemetry system, aimed at real-time monitoring of variables during cycling practice, in order to evaluate the effect of inflation pressure on RRF under real-world conditions (3). The main objective is to describe the relationship between tire inflation pressure and RRF, to determine the optimal pressure, in order to optimize cyclist´s mechanical efficiency and, consequently, their performance. 

Methods 

A cyclist at the Zaragoza velodrome performed 71 one-kilometer trials, all recorded under similar weather conditions. Six different inflation pressures [4, 5, 6, 7, 8, and 10 bar] were tested using 25mm Continental Gator Skin tires. A pedal-based power meter from Favero [Favero Electronics SRL, Arcade TV, Italy] and a magnetic speed sensor were installed on the cyclist’s bike, along with a weather station [Kestrel Meter 5500, NK Company, USA] to measure air density, and a digital scale to record CBS weight [72.38 kg]. The new developed telemetry system captured and synchronized sensors data in real time, applying a linear regression model instantly for each pressure value to calculate the RRF and aerodynamic coefficient [CdA]. After the trials, quadratic regressions analysed the relationship between pressure and RRF. In addition, ANOVA and Student’s t-tests determined the statistical significance between the different pressure conditions. 

Results 

The analysis observed a quadratic relationship with a high goodness-of-fit [R² = 0.9413]. The lowest RRF values appeared at intermediate pressures of 6, 7, and 8 bar, while both the lowest [4 and 5 bar] and highest [10 bar] pressures showed significantly higher RRF values. These differences resulted in up to 9% more absolute power required by the cyclist to maintain the same speed. The CdA remained stable throughout the study [CV = 2.62%] 

Conclusion 

This study highlights the significant influence of tire inflation pressure on rolling resistance, revealing a quadratic and not a linear relationship when tested on real surfaces with some roughness. Practical applications involve using low-cost telemetry systems to determine the optimal tire pressure for each cyclist based on surface characteristics, thereby reducing RRF and improving efficiency and performance. Future research can replicate this study testing different surface roughness and tire types. 

References 

Debraux P, Grappe F, Manolova AV, Bertucci W. Aerodynamic drag in cycling: methods of assessment. Sports Biomech. September 2011;10(3):197-218. 2. Martin JC, Milliken DL,  

Cobb JE, McFadden KL, Coggan AR. Validation of a Mathematical Model for Road Cycling Power. J Appl Biomech. August 1998;14(3):276-91. 

Bertucci WM, Rogier S, Reiser RF. Evaluation of aerodynamic and rolling resistances in mountain-bike field conditions. J Sports Sci. 2013;31(14):1606-13. 

Grants and funding sources 

Regarding grants and funding sources, the authors declare no conflicts of interest. However, they would like to acknowledge the companies “Bikone Bearings” and “Mecanizados PG” for providing some of the materials used in this study, as well as the Aragonese Cycling Federation for granting access to the facilities of the Zaragoza Municipal Velodrome