An 18-year-old man is in hospital with serious injuries after a crash involving his bicycle and a vehicle on the A17 in Sutton Bridge.
Police wish to hear from anyone who saw the collision or a silver Ford Mondeo driving in the area around that time.
Anyone with information should call Sergeant Gell on 101 or Lincolnshire Police Collision Hotline on 01522 885588, quoting incident 357 of October 31.