There is also a study that shows other traffic participants engage in riskier overtaking when a cyclist wears a helmet. Instead of leaving 1.5 m space when the cyclist is on the side of the car, drivers leave an average of 0.5 m space for cyclists wearing a helmet.
If I remember correctly, drivers see helmets as increased safety for the cyclist and feel they can engage in less safe behavior because it evens out.
Edit: For exact distances, see the paper (doi: 10.1016/j.aap.2006.08.010).
although it seems to make some sense, I am never treating any cyclist differently, be it granny or some racer or anything between, whatever the dress and equipment. It's a moving obstacle to be overtaken asap, with some extra room around them necessary.
the only 2 things that matter - speed of the cyclist and the stability of their ride (ie keeping straight path close to side of the road which I do on bike is ideal, aholes driving 2-3 next to each other taking full lane and sometimes more, chatting together and going left to right is on the other side of the spectrum)
It seems to have been “Drivers overtaking bicyclists: Objective data on the effects of riding position, helmet use, vehicle type and apparent gender”[1] (doi: 10.1016/j.aap.2006.08.010).
This study is cited in every discussion of helmet use, yet it was barely scientific -- the author was his own test subject, and there has been no attempt at replication.
If I remember correctly, drivers see helmets as increased safety for the cyclist and feel they can engage in less safe behavior because it evens out.
Edit: For exact distances, see the paper (doi: 10.1016/j.aap.2006.08.010).