Apparatus for mounting a sliding door for horizontal movement in a frame which has an upwardly-extending upper track and an upwardly-extending lower track which comprises a horizontally-elongated rib defining a generally vertically-oriented plane. The apparatus includes a sliding door panel which includes upper and lower generally horizontal rail members. Means are provided to mount the sliding door panel to the upper track for horizontal movement along the track. The apparatus also includes an extruded elongated element suspended from the lower generally-horizontal rail member of the sliding door panel. The elongated element is disposed for free reciprocating vertical movement relative to the lower generally-horizontal rail member. The elongated element is provided with a length substantially the full length of the sliding door panel. The element is also provided with a slot which is formed in a bottom surface of the element. The slot extends substantially the full length of the bottom surface of the elongated element, the slot receiving the horizontally-elongated rib defined by the lower track therein.