A bicycle with the serial number F110415484 (pictured) was stolen from Westbourne between 4 and 19 October from a block of flats along Lindsay Road.
White with black and green markings, the Cannondale pedal cycle was locked to a bracket and another cycle with a heavy duty cable lock and a separate chain lock.
There were a number of extras on the bike including light brackets, an under seat saddle bag and the fittings for shoes had been changed.
Police Constable Luke Davis, of Bournemouth police, said: “I urge anyone who witnessed the theft or may have seen anything suspicious in the area at the time to come forward. It is believed the offender may have gained access over a wall on Poole Road.
“I would also like to hear from anyone who knows of the whereabouts of the pedal cycle or has been offered such a bike in strange circumstances or for an unusually low price.
“I would like to remind people to be vigilant and report any suspicious activity to the police.”
Witnesses and anyone with information should call Dorset Police in confidence on 101, quoting incident number 17:89. Alternatively, call the free and anonymous Crimestoppers line on 0800 555 111 where mobile phone tariffs may apply.