Some bike racks attach to the roof or the rear of a vehicle and can usually carry two to five bicycles. This photo shows a typical rear-mounted bike rack carrying four bicycles. This type of bike rack is often used for transporting bicycles on cars.
Car-mounted bicycle racks may be fastened to the trailer hitch, strapped to the rear of the car, or mounted to the roof. Roof-mounted racks may be used to transport bicycles as well as luggage, skies, kayaks, canoes, and other recreational equipment.