Abstract: Disclosed is a lockable clamping apparatus for securing a bicycle to the rail of a pick-up truck bed having a generally L-shaped lengthwise extending portion. The clamping apparatus includes outer clamping means for engaging the outer facing surfaces of the truck bed rail's L-shaped portion and inner clamping means for engaging the inner facing surfaces of the truck bed rail's L-shaped portion. The inner and outer clamping means are movably, preferably pivotally, connected to each other so that they can be moved, preferably pivoted, between an open mounting position and a closed clamping position. The clamping apparatus is mounted on the truck bed rail when it is in its open mounting position. When the clamping apparatus is in its closed clamping position, the first and second clamping means tightly engage the L-shaped portion of the truck bed rail to secure the clamping apparatus thereto.