A sudden rise in cycle thefts has led police in Harrogate to carry out extra patrols of the town.
Cyclists are also being urged to do their bit to improve security after six bicycles were reported stolen from Harrogate town centre in the last week alone.
North Yorkshire Police has been notified of 21 bike thefts in the area since April.
The thefts have been occurring at all times of the day and night, with the value of the bikes stolen ranging from a few pounds to a few thousand pounds.
Inspector Alex Langley, of Harrogate Town Centre Neighbourhood Policing Team, said: “The advice I would like to offer to cyclists is that parking your bike at the rear of your work premises may be the most convenient for you to get in and out of work – but is it the safest place for your bike?
“Often people feel that because they have bought a cycle lock that means their bike is secure and will not be stolen.
“Unfortunately, criminals have access to bolt croppers and wire cutters, and locking a bike to a fire escape in an isolated back street or private area only gives criminals more time and freedom to remove your lock and then make off unseen and unheard.
“If possible, always ensure your bike is secured inside a garage or shed, and do not risk leaving it unattended overnight.”
Anyone with information about the cycle thefts should call police on 101 or Crimestoppers anonymously on 0800 555111.