Cyclists own a bike for an average of two years before it is stolen, according to a study.
Research by insurance firm LV= showed that one in five thefts happens within six months of a bike being bought, but a third of victims do not bother to report the crime to police.
A survey of 2,000 adults showed that one in five has had a bike stolen, with most thefts outside their home.
Around 5% of victims have had three or more bikes stolen.
John O'Roarke, managing director of LV= home insurance, said: "Bike theft is a growing problem in the UK with many cyclists having had a bike stolen several times over.