A motorcyclist from Portslade was seriously injured in a crash on the A27 at Falmer as he was riding towards Lewes.
Sussex Police said: “At 12.43pm on Sunday 18 May police were called to the A27 eastbound at Falmer where a 125cc motorcycle had been travelling between slow-moving lines of traffic on the dual carriageway when it was in collision with three vehicles.
“The motorcyclist, a 21-year-old Portslade man, suffered serious but not life-threatening injuries and the A27 was temporarily closed in both directions to allow the Kent, Surrey and Sussex Air Ambulance to land at the scene.
“The casualty was eventually taken to the Royal Sussex County Hospital by land ambulance and detained for treatment.”
Anyone who saw what happened or who may have other information is asked to phone Sussex Police on 101 or email firstname.lastname@example.org.