Nineteen bikes have been stolen in 23 days in two seaside towns.
Since the start of the month, 19 bicycles have been reported stolen in Hastings and St Leonards.
The incidents range from chained up bikes on the street to locked up bikes in sheds.
Inspector Chris Veale, of the Neighbourhood Police Team, said: "I suspect we have several thieves operating across the town.
"My advice is to see that your bicycle is as secure as you can make it. Invest in a good quality chain lock and consider having your bike security marked.
"Do remember that you can also register property, including bikes and electrical items, on the free Immobilise website - www.immobilise.com
"This is used by police forces nationwide and means that if you have registered property that is stolen and subsequently recovered, it can be returned to you."
Police are currently visiting cycle shops and second-hand dealers with Immobilise leaflets to further raise awareness.