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.
"Cyclists should take care not to alert thieves to bikes in their home by leaving them in view or leaving bike racks on their car when not in use."