Roof rack system for cars incorporating removable traverses

The system has a side frame (11) with a housing that cooperates with a cam (24) so as to prevent disintegration of the side frame and cross pieces when the cross pieces are in a rest position. The cross pieces move in rotation with respect to the side frame between a rest position and a hooking/unhooking position on a predetermined angular track to pivot the cam in the housing. An independent claim is also included for a motor vehicle including a roof rack system.