The poll of more than 1,000 Scots found 73 per cent did not know the potential consequence of failing to leave at least a car’s width when passing.
Cycling Scotland, which commissioned the research, is raising awareness of the risks to cyclists in a new campaign.
Police Scotland has meanwhile launched Operation Close Pass to make roads safer for cyclists. The initiative sees plain-clothes officers cycling with a cameras on their bike. When they are passed too closely by a car, the cyclist radios details to colleagues further up the road, who pull over the motorist.