[QUOTE 1415029"]
If you're talking about the Bristol study, I think you are talking it up a bit. It was a very small study that didn't show anything. It made some suggestions, but that's about all.
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I think you mean the Bath study, Walker, I. (2007). Drivers overtaking bicyclists: Objective data on the effects of riding position, helmet use, vehicle type and apparent gender. Accident Analysis and Prevention, 39, 417-425.
"Overall, the results demonstrate that motorists exhibit behavioural sensitivity to aspects of a bicyclist's appearance during an encounter" is more than a suggestion and "shows" something. It also showed
"The relationship between rider position and overtaking proximity was the opposite to that generally believed, such that the further the rider was from the edge of the road, the closer vehicles passed. Additionally, wearing a bicycle helmet led to traffic getting significantly closer when overtaking. Professional drivers of large vehicles were particularly likely to leave narrow safety margins."