Keen bike-riders wanting to cycle their petrol-powered bikes on roads are urged not to do so as it can result in injury.
The bicycles were illegal and posed risk to riders, Senior Sergeant Ian Campion said.
The petrol-powered bikes could reach speeds over 50km/h and could become difficult to control, he said.
It was also hard to use a brake efficiently.
A bicycle fitted with the 50cc or smaller petrol-powered motor fell within a moped classification and those with larger engines fell within a motorcycle category.
However, a petrol-powered bicycles was unable to meet the safety standards and legislative requirements for mopeds and motorcycles and couldn't be used on the road.
Mr Campion warned riders could be heavily fined for using these bikes.
A list of infringement fees:
Unregistered motor vehicle $150
Unlicensed motor vehicle $100
Unlicensed driver $400
No motorcycle helmet $50
No tail light on moped $55
Motorcycle / moped failed to use headlamp or day-time lamp during day $100
Operated moped without a brake on both wheels $150