1. Conclusions

Overtaking motorists pass closer to a bicyclist when the rider wears a helmet, rides away from the edge of the road, is male, or when the vehicle concerned is a bus or heavy goods vehicle. Based on previous work on drivers’ perceptions of bicyclists, we have suggested that many of these effects are the result of motorists making assumptions about bicyclists’ behaviours based on a brief visual assessment of their likely experience levels. We argue that these assessments can only ever provide a poor guide to the likelihood of a collision occurring and would encourage efforts to warn motorists of the assumptions they are making and the fallibility of these.