Police and other emergency services were called to Chichester Road at 7.30am on Tuesday, June 28 following the collision, which involved a motorcycle and several other vehicles.
The road was closed and a cordon established while police investigated the incident, but it was opened yesterday afternoon.
Officers later arrested a 31-year-old man from Portsmouth on suspicion of causing death by careless or inconsiderate driving and failing to stop at the scene of a road traffic accident. He has been bailed, pending further enquiries.
Police have urged anyone who saw the collision, or anyone with relevant CCTV or dashcam footage in the area at the time to report it to Sussex Police online or email: [email protected] and quote Operation Buckhurst.