> “ In 2006 he attached a computer and an electronic distance gauge to his bike and recorded data from 2,500 drivers who overtook him on the roads. Half the time he wore a bike helmet and half the time he was bare-headed. The results showed motorists tended to pass him more closely when he had the helmet on, coming an average of 8.5 cm nearer.”

This study proves nothing about rider safety. What matters here is actual accidents, and most bike accidents do not even involve a car. The study only proves that motorists would pass about 4 inches closer to author of the study when he had a helmet on. Motorists were not frequently hitting the author.