Abstract: A chair having a chair seat and a chair back includes a means for controlling the tilt of the chair back relative to the chair seat, the tilt means comprising a control body mounted beneath the chair seat and a pivot body pivotably mounted beneath the control body. A spring is operatively disposed between the control body and the pivot body. The control means comprises means for limiting the range of angular motion of the pivot body. Further, the locations of the control body, the pivot body, and the rod about which the pivot body pivots are each optimized to reduce the shear force that is applied to the user's back when the user exerts a force against the chair back.