A tilt mechanism is configured for adjustment of a tension applied by a chair back. The tilt mechanism includes a base, a back bracket tiltably supported on the base, and a rocker coupled to the back bracket so as to be moveable relative to the back bracket. The rocker has a pivot axis and pivots about the pivot axis when the back bracket tilts relative to the base. An energy storage mechanism is coupled to the rocker to exert a force onto a portion of the rocker. An actuating mechanism is coupled to at least one of the rocker or the energy storage mechanism and is configured to alter a distance between the pivot axis and the portion of the rocker at which the force is exerted onto the rocker, thereby altering a length of a lever arm.