A quiet beachfront town north of Auckland was targeted by an alleged thief, who police say got away with more than 20 bikes, worth at least $20,000, during his crime spree.

Over the last seven months Orewa has been plagued by someone residents believe took advantage of the community's laid-back attitude to security.

Sergeant Kylie McIvor said towards the end of last year police noticed a clear spike in bicycles - mainly mountain bikes worth more than $500 each - being taken.

Though the first incident was reported in March last year, the alleged offending really gained momentum in August when six people were targeted.


There was a lull for a couple of months before November, during which police say there were eight more thefts.

Some nifty police work saw officers collate the crime reports made by members of the public and match them against North Shore second-hand dealers' records.

Though most of the stolen property had been on-sold by the unwitting dealers, inquiries led them to a 34-year-old Orewa man.

Further investigation uncovered a dozen allegedly stolen bikes for which there was no corresponding theft reported.

Ms McIvor urged members of the public to contact police, ideally with the serial number of their bike, if they believed they were a victim.

"If people have that proof it'll be very easy for us to identify [their bike]," she said. "Bringing in a picture can also help."

Orewa resident Warwick Schollum, who lives by the beach, said he used to prop his bike against the house on the back deck.

In August he woke up and it was gone.

He told the Herald it was chilling to think someone had cased his property before sneaking in during the night.

"It's not just one bike you think of, it's the other implications," Mr Schollum said. "If I'd woken up and gone out there I might've got a whack over the head."

He said it was the kind of town where people left their windows and doors open but that was no longer the case for him.

Due to the spate of offending, Mr Schollum said Orewa College had also taken action, moving their bike stand from the edge of the school to an area more visible to staff and students.

Joseph Michael Hart, 34, appeared in North Shore District Court this month charged with 22 counts of theft and entered no plea.

His case will be called again next month.

Meanwhile Ms McIvor said anyone who believed their bike had been stolen should contact the Orewa police station on 09 426 4555.