Cyclist hit by car suffers head injuries

A Sydney cyclist has been airlifted to hospital with a serious head injury after being hit by a car on a main road.

The man, believed to be in his 50s, was hit by the car just before midday on Wednesday while riding on a main road in the Northern Beaches.

He was wearing a helmet and protective gear when he was knocked unconscious, however, he wasn't carrying identification and police are yet to find out who he is.

He has been airlifted to Sydney's Royal North Shore Hospital.