A ring binder mechanism that includes a housing, first and second hinge boards positioned in the housing that cooperate to define a slot having a closing edge and an opening edge. The hinge boards are pivotable between open and closed positions. A plurality of pairs of semi-rings include first and second ring members mounted on the first and second hinge boards, respectively. A travel bar is positioned below the hinge boards and moveable with respect to the housing and the hinge boards between an open position and a closed position. The travel bar includes at least one top bar extending from a top surface thereof that includes inclined opening and closing surfaces. The top bar extends through the slot in the hinge boards and is biased toward the open position. The inclined opening surface of the top bar contacts the opening edge of the slot to pivot the first and second hinge boards to the open position.