More than 1 in 4 cyclists in London have had their bike stolen, according to a new report by insurance firm "LV=".
The report shows that the black market for stolen bikes is booming and could be worth £58 million nationwide.
John O'Roarke, LV= Managing Director, says not enough people buying second-hand models ask about the bike's history.
"It is also worth looking to see whether a postcode or serial number has been scratched over, which is often the case with stolen bikes.
"Otherwise they'll simply perpetuate the bike black market, which could result in their own bike being stolen too."