University of Reims, France

This study has been carried out by Samuel Crequy and Xavier Chiementin from the Research Group in Engineer’s Sciences at the University of Reims, and Georges Kouroussis from the University of Mons.

Recent studies have demonstrated that more than 7 minutes of vibration exposure on a cobblestone road can have detrimental effects. The aim of this study is to reduce vibration effects on the bike-rider system by applying the Operational Modal Analysis (OMA) method.

The OROS system was selected for its “on-bike” measurements capabilities. The OR35 8 channels instrument was installed in the rider’s backpack (see picture). Data acquisition was processed in multiple runs with 2 references and 14 responses. The first stage was to check repeatability of OMA on sections of cobblestone road (10 passes). The second stage was to acquire the 14 responses on 2 passes for each configuration.

Autonomy, size and weight of the OROS system enabled accurate results to be collected without any influence on the bike-rider system.

OROS Modal software was used for post-analysis. Modal parameter extraction and a shape mode of the bike were provided for each speed and rider mass.

The study led to bike design adjustments for each combined configuration of rider, road and speed.
Thanks to the real-time capabilities of OROS instruments, embedded measurements were successfully monitored during acquisition stages.

OROS latest technology updates enabled the monitoring measurement campaigns from a vehicle close to the bike under test, thanks to the Wi-Fi now integrated in the Teamwork instruments. See the latest features of OR35 Teamwork.

The complete scientific research article was presented at the Analyse Vibratoire Expérimentale (Experimental Vibration Analysis) conference in France, in November 2016.

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FdJ is a cycling team taking part in the Tour de France. In preparation for next year’s race, the team has opted to undergo vibration optimization to give them better performance on cobblestone sections of the race stages. In collaboration with Reims University, the dynamics of bike / wheels / tires / human body are measured using OROS equipment (OR35 noise and vibration analyzer), in a pack on the rider’s back.

Initially, measurements are made on indoor tracks for identification of the normal modes. Next, measurements are carried out on cobblestone roads themselves. Sensors are fixed on the saddle tube, the stem, and on the rider’s arms and buttocks. Pedal force is also recorded.

After mode/ performance analyses, specific combinations of wheel types, tire pressures and bike frame dimensions are recommended for each rider.

See also an OROS analyzer embedded by a bikerider from the FDJ team (French language)