A study by scientists at the University of Bath suggests there is little more cyclists can do to make themselves visible, with some drivers ignoring high-visibility clothing and still risking safety with dangerous overtaking moves.
According to the report, between 1% and 2% of drivers pass "dangerously close" when trying to manoeuvre around a biker.
The average gap has now reduced from 179cm in 1979 to 118cm today.
The researchers are calling for the responsibilities of road safety to move away from cyclists themselves, with more work put into improved bike networks and refined driver behaviour.
Project leader Dr Ian Walker, from the university's psychology department, said: "Many people have theories to say that cyclists can make themselves safer if they wear this or that.
"Our study suggests that no matter what you wear, it will do nothing to prevent a small minority of people from getting dangerously close when they overtake you.
"This means the solution to stopping cyclists being hurt by overtaking vehicles has to lie outside the cyclist.
"We can't make cycling safer by telling cyclists what they should wear. Rather, we should be creating safer spaces for cycling, perhaps by building high-quality separate cycle paths, by encouraging gentler roads with less stop-start traffic, or by making drivers more aware of how it feels to cycle on our roads and of the consequences of impatient overtaking."
Copyright Press Association 2013