A recent study by psychologist Ian Walker from the University of Bath examines if the amount of space car drivers give people on bicycles when overtaking is related to the outfits worn. It concludes that is does not seem to matter, except if a person wears an outfit that includes the word “Police”.
The study was based on 5690 overtaking events. The mean overtaking distance was 117 cm. It is interesting to note that thirty years ago in a study in the same area the mean passing distance was 179 cm, and in 2007 it was 133cm. This indicates that the space given to cyclists by motorists is reducing. 1-2% of overtakes were 50 cm or less.
A small proportion (1-2%) of overtaking drivers passed within 50 cm of the rider no matter what was being worn.
There is evidence emerging to suggest that high-visibility clothing might not be as good at increasing conspicuity as is often supposed and might lead to a false sense of security
The study suggests that there is little people on bicycles can do to prevent the very closest overtakes. The authors of the paper suggest that the optimum solution to the very closest overtakes will not lie with bicyclists themselves, but instead need changes in infrastructure, education or the law to prevent drivers getting dangerously close when overtaking bicyclists.