The bicyclist and driver were both traveling northbound on Brookhurst Street, just south of Ellis Avenue, just before the 1 a.m. crash, said Sgt. Donald Farmer of the Fountain Valley Police Department.
The victim, identified only as a male, died at the scene.
According to investigators, the driver fled the location in a vehicle described as possibly a red Ford Mustang with front-end damage.
The two halves of the bicycle were found almost a block apart.
Anyone with information about the incident is asked to call Fountain Valley police at (714) 593-4485.