TORONTO (Reuters) – Motorists give greater leeway to cyclists who do not wear safety helmets, according to a study by a academic in Britain who was hit by traffic twice as he rode his bike to carry out his research.

Researcher Ian Walker from the Department of Psychology of Britain’s University of Bath found drivers were up to two times more likely to get close when passing cyclists wearing helmets than when overtaking bare-headed pedalers.

He said wearing a helmet might therefore make a collision more likely, but a safety-advocacy group cautioned against giving up a helmet’s protection against head injury in hopes of avoiding a crash.

To conduct his experiment, Walker rode a bicycle fitted with a computer and an ultrasonic distance sensor and recorded data from more than 2,500 overtaking motorists.

He spent half his time wearing a helmet and half bare-headed. He says he was struck by a bus and a truck while wearing the helmet but was uninjured.

Walker, whose research has been accepted for publication in the international journal Accident Analysis & Prevention at a date not yet set, said his study followed previous research that found many drivers saw cyclists as a group of “lycra-clad street-warriors..”

“This may lead drivers to believe cyclists with helmets are more serious, experienced and predictable than those without,” he said in a statement released on Tuesday.

Walker found drivers passed an average of 3.3 inches (8.5 cm) closer to cyclists with a helmet than without, giving cyclists the room needed to avoid drain covers and potholes.

As part of his experiment, Walker also donned a blond wig and found drivers gave him an average of 5.5 inches more space when they passed what appeared to be a female cyclist.

“We know helmets are useful in low-speed falls, and so definitely good for children, but whether they offer any real protection to somebody struck by a car is very controversial,” said Walker. “Either way, this study suggests wearing a helmet might make a collision more likely in the first place.”

A spokesman for Britain’s Royal Society for the Prevention of Accidents said the study highlighted the vulnerability of cyclists and the need for drivers to take greater care.

“But we would not recommend people stop wearing cycle helmets because of this research. Helmets have been shown to reduce the likelihood of head and brain injuries in a crash,” said the spokesman.

This story is a replication of an article by Reuters and Yahoo News