Detective Sergeant Colin Grenfell said there had been 46 thefts from vehicles reported in the past 18 days, which was close to average for Bendigo.

"It's one of our most common crimes," Detective Sergeant Grenfell said.

"Mostly the thieves are not breaking into cars. The thefts are mostly from unsecured vehicles in driveways, under carports and in the street," he said.

"We are asking that people keep their cars secure and remove valuable items."

Detective Sergeant Grenfell said the thefts mostly occurred at night.

"They are opportunistic thefts where cars are being left unlocked and valuables being left in them," he said.

"People are leaving wallets, Navmans, loose cash and sunglasses in their cars. Some people lose quite expensive property.

"Some thefts are occurring at shopping centres but they're mostly in residential areas."

Detective Sergeant Grenfell said thefts from cars was a high-volume crime in other areas too.

Victoria Police has issued the following information and advice to help prevent thefts from vehicles:

• Most thieves break into cars because they see something they want inside. 

• Drivers should hide valuable items out of sight before parking their car.

• Victims of thefts from cars are often uninsured or have an insurance excess exceeding the value of the lost items.

• Owners should mark accessories and valuables kept in cars with a "V" and their driver's licence number.

Meanwhile, police are looking for the owner of a stolen bicycle they have recovered.

Bendigo's Senior Constable Stewart Probst said the bike was stolen near Champions Supa IGA at Kangaroo Flat in late March.

"We have charged an offender with the theft," Senior Constable Probst said.

"The bike is silver coloured and it's very distinctive. The owner will be able to describe it in detail," he said.

If you think you own the bike, phone Senior Constable Probst on 5448 1300.