Cyclists in Brighton and Hove are more likely to have their bikes stolen than almost anywhere else in the country.
The city has the eighth highest number of bicycle thefts in the UK, according to a new survey.
As riders take advantage of the spring warmth, police say they receive an average of two reports of bicycle thefts a day, chiefly in the city centre.
Crime Reduction Manager Paul Knight said: "The number of bikes stolen accounts for a large amount of the thefts we see in the city."
Officers are using "trap bikes" to catch the thieves.
The bikes are fitted with miniature tracking devices allowing police to hunt them down and arrest them.
Mr Knight said cyclists should lock their bikes even when they are only leaving them for a short time.
He recommended D-shaped steel shackle locks, rather than padlocks and chains.
He said: "Wherever possible, you should lock your bike to something solid and in view of a CCTV camera. If your wheels come off easily, remove the front wheel and lock it to the frame and back wheel, using a second lock if necessary.
"Keep a list of the make and model of your bike along with details of the frame number, its colour and any accessories or special features. If you can, take a photograph and keep it with these details. Lock It, list it, don't lose It."
Police are appealing for members of the public who see people with boltcutters or saws trying to remove locks or chains to contact them.
They are planning a series of events over the summer to promote bike security, and are trying to arrange a stand at the London to Brighton bike ride on June 17.
The city is a Government-designated Cycle Demonstration Town, with up to 2,000 bike journeys a day made on the seafront path.
The news comes after it was revealed heartless thieves have stolen three push bikes from pupils at a special educational needs school.
The bikes were taken last week in a break-in at Cedar Centre, Lynchet Close, Hollingdean. The total cost of the theft to the school is £500.
Staff member Lyn Dickson said: "It's quite a lot of money for us to lose as we are on tight finances. The children have missed out a lot though in not having the bikes. They're terribly upset."
If anyone has any information, please call Sussex Police on 0845 6070999.
Have you had your bike stolen in the city? Leave your comments below.
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