The thule backpac 973 static rear rack mount system carries 2 bikes 3 by adding adapter 973 23 and 4 by adding adapters 973 23 973 24 the thule backpac carrier is easy to fit and attaches to the the rear door using rubber coated fixtures while the raised position means your rear light and number plate are visible this rear car rack has an extendable wheel tray to accommodate larger bikes the fully adjustable and detachable arms can be locked for security and folds flat for easy stor