The collision occurred shortly before 12:30 a.m. Thursday morning on the eastbound 60 Freeway near Nason Street, according to the California Highway Patrol.
The victim was riding a 2009 Suzuki motorcycle in the No. 2 lane when a black sedan approached from behind "at a high rate of speed," the CHP said in a statement. The car struck the back of the motorcycle, ejecting the rider.
The victim suffered major injuries and was transported to Riverside University Health Systems Hospital, the Highway Patrol said.
A witness who stopped at the scene to help the motorcyclist provided the dashcam video to authorities.
Anyone with information about the crash is urged to call the CHP's Accident Investigation Unit at (951) 637-8000.
