Experimental Comparison of Speed-Dependent Rolling Coefficients in Small Cycling Tires

Abstract

In this article, the methodology and results of an experimental campaign on small and slick bicycle tires are presented. The test was developed to compare the rolling resistance of tires to be used in high-speed competitions for streamlined human-powered vehicles. After an explanation of the theoretical background for the measurement, the test-rig and the adopted procedure to measure and subtract aerodynamic effects are presented. The obtained data show that the rolling resistance coefficient has a nonlinear dependency from the speed between 45 and 145 km/h. The data comparison points out a decrease in rolling losses up to 54% by switching from a butyl to latex inner tube on the same tire, whereas no significant difference is detected between the latex tube and tubeless configuration. An estimation of the impact on racing performance is provided, showing that selecting the best option could save up to 19% of the overall effort energetic cost, which means a higher final speed can be achieved with the same rider effort. Finally, a speculative analysis is proposed that considers different functions to fit the obtained data, pointing out the need for experimental measurements on the very-low-speed region to achieve a better understanding of the entire rolling resistance behavior with respect to speed.

Simulation of transient rolling resistance of bicycle tyres at various ambient temperatures

“…In addition, the tube type and speed dependency of rolling resistance has been known for many years. Baldissera et al [ 6 ] confirmed this increase in rolling resistance coefficient with increasing speed in their experiments. Nonetheless, this increase has minimal relevance for utility cyclists since these changes occur at velocities much higher than are typical for utility cyclists.…”

“…Depending on the application, riders attempt to reduce some of these driving resistances in order to reduce driving effort. For example, rolling resistance and aerodynamic forces are reduced in competitive cycling to maintain high acceleration and high speeds on a given track, including ascending slopes [ 6 ]. In contrast, utility cyclists try to avoid hills to reduce the cycling effort required [ 7 ] and are willing to pedal a longer distance instead.…”

On Rolling Resistance of Bicycle Tyres

“…Baldissera [9] performed coast-down tests with a full fairing recumbent bike to evaluate the linear dependent and the inverse linear on vehicle speed dependent rolling resistance coefficients. Last year Baldissera published the results of experiments on a drum [10] again with focus on high speed.…”