A cyclist is in a critical condition in hospital following an accident yesterday afternoon.
Police are appealing for witnesses to the collision in Nyetimber Lane, Rose Green, near Bognor.
It happened at about 2.45pm near the road's junction with Nyetimber Close.
A white Fiat Panda car, being driven by an 84-year-old man, was in collision with a black Giant 6000 pedal cycle, being ridden by a 61-year-old woman.
Both people live in the area.
The woman suffered serious head injuries and was flown by air ambulance to Southamton General Hospital.
The car driver was unhurt.
He was arrested on suspicion of failing to stop and causing serious injury by dangerous driving.
He has been baikled until September 1 while enquiries continue.
The road was closed to traffic either side of the scene for two hours while emergency services dealt with the incident.
Sergeant Rob Baldwin, of the West Sussex road policing unit, said: "We are grateful for the patience of motorists whose journeys were affected."
Witnesses are asked to call Sussex Police on 101 or email firstname.lastname@example.org, quoting Operation Alliance.