The SportRack SR4624 DownShift Plus is a fork mounted roof bike rack. The DownShift Plus is designed to carry a bicycle with a 9mm fork. Your bike is attached onto the rack using a locking quick release skewer which clamps onto your front forks along with a rear wheel strap which mounts through your back tire. The DownShift Plus can carry a bike with a wheelbase of up to 48 inches and a tire width of less then 2.3 inches. The SportRack DownShift Plus utilizes universal mounting hardware giving you the flexibility to mount the bike rack onto a wide variety of crossbars right out of the box.