Gravel Bike Vibrations

The purpose of this pilot study was to explore the vibration exposure of Gravel bikes at different tire pressures. Therefore, 9 cyclists (73.7 ± 10.2 kg, 1.78 ± 0.06 m) rode a 150 m flat gravel section at a constant speed of 25 km/h with three tire pressure conditions (1.5, 2.5, 3.5 bar). Horizontal and vertical accelerations at the front dropout (FDO) and rear dropout (RDO) were recorded. Reducing the tire pressure from 3.5 to 1.5 bar resulted in a significant decrease in the resulting acceleration at the FDO from 3.41 ± 0.18 g to 2.07 ± 0.07 g and at the RDO from 2.78 ± 0.14 g to 1.56 ± 0.07 g. When comparing the ratio of horizontal and vertical rms of acceleration, ratios of up to 0.9 for the FDO and up to 0.47 for the RDO were found. This indicates that horizontal accelerations, especially at the FDO contribute considerably to the overall vibration exposure of the bike. The two main conclusions are that (I) damping systems in gravel bikes should take into account not only vertical but also horizontal accelerations and (II) tire pressure adjustment has a similar potential for vibration management on gravel as more complex damping systems.