If bikes are not properly and securely locked to a hitching post, they could be stolen, Senior Sergeant Appley said.
"Every push bike owner should be taking care to lock up or store bikes wisely - especially outside universities, gyms, malls and high schools.
"People should consider a high-quality D-lock or similar to deter would-be thieves. When you first buy your bike, please ensure that you record its serial number and take a photo of the bike."
He said you should put the details of that number somewhere safe and tell your insurance company.
"These thefts are happening during daylight hours. People are having their daily transport stolen.
"Also, when looking to buy bicycles online, be careful that you are not buying a stolen push bike."
The majority of the stolen bikes are being sold via online market places.
"We'd recommend you purchase from authentic sellers and genuine retailers, and websites based in New Zealand."