Cyclists are being warned to lock their bikes up properly after more than 300 were stolen in six months.
Police said bicycles have been going missing at an "alarming rate" in Gosport, Hampshire.
They have been laying on more patrols in known theft "hotspots", which have resulted in 47 arrests since January.
Signs warning people to make sure their bikes are secure are also being put up around Frimley Gardens, Ferry Gardens and a number of schools and colleges.
Stewart Kybert, Gosport's crime reduction officer, said: "Bikes have been going missing at an alarming rate over the last six months, mainly because people are leaving them insecure.
"I can not stress enough how important it is for cycle owners to take cycle security seriously.
"Otherwise they could be the next person reporting their cycle missing."