Influence of peloton configuration on the interaction between sport cyclists and motor vehicles on two-lane rural roads

Cycling is a common activity on Spanish two-lane rural roads, mainly associated to sport and leisure, which resulted in 54 deaths in 2014. There is no scientific evidence about the risks associated to the interaction with motor vehicles of cyclists riding in a peloton. According to Spanish regulations, up to two cyclists can ride in parallel. This study compared different peloton configurations riding on a two-lane rural road segment. Three amateur cyclists rode along a road segment individually and grouped in pelotons with preset configurations: single bicycles, two bicycles in parallel, two in line, and different groups of three cyclists. Motor vehicle overtaking was observed and characterised from video cameras installed in the bicycles; speed and clearance were measured thanks to laser rangefinders on board. Moreover, the subjective risk perception at every overtaking event was recorded. Objective and subjective measures identified risky overtaking manoeuvres (low lateral clearance, high speed of vehicles, or high-risk perception). When cyclists rode in parallel, lower lateral clearances were found. At the same time, the overtaking vehicle speed was higher when individual cyclists were passed. These provided scientific support for criteria to ride in a peloton on two-lane rural roads.