POLICE are appealing for witnesses after a driver involved in a collision with a motorbike in Croxley Green on Friday (April 9) failed to stop.
The crash happened at about 4.30pm on the roundabout by the Harvester pub in Watford Road.
The 22-year-old riding the motorcycle, a green Kawasaki, suffered serious injuries and was taken to Watford General Hospital.
The car involved, believed to be black in colour, did not stop at the scene.
Sergeant Andrew Naylor from the road policing unit said: "We are appealing for the driver of the vehicle to call us to help with our investigations.
"Alternatively, if you saw the collision, or have any information that may help with our enquiries, please call police on 0845 33 00 222 or Crimestoppers anonymously on 0800 555 111."