A spate of moped and motorbike thefts in Hounslow has prompted a warning to owners that their bikes could also be eyed up by thieves.
They have urged drivers to better secure their bikes to avoid falling victim to the crimewave themselves.
PC Will Lowery, of Feltham neighbourhood police team, said steering locks were not the most effective security devices as they could too easily be broken.
He advised owners to securely chain the bike's wheels to something or, where possible, to park the vehicle off the street.
"Moped theft is an issue, especially in Feltham, and we would urge owners to take extra care to secure their vehicles," he said.
"Some of the thieves, especially those targeting more expensive motorbikes, are obviously quite experienced.
"The cheaper mopeds tend to be stolen by teenagers who drive them around doing wheelies."
PC Lowery said the stolen vehicles seized in recent weeks ranged from a £14,000 top-of-the-range motorbike to cheap mopeds of the kind typically used to deliver pizzas.
They have been recovered from Crane Park and Feltham Park, among other areas.