Quick-release clamp with secondary retention mechanism

A quick-release bicycle accessory, comprising:

• a first rail having a first interlocking profile, a rail profile axis, and an opened channel having a first end and a second end passing through the first rail perpendicular to the rail profile axis;
• a second rail having a reciprocally shaped second interlocking profile, a top surface, and a retention channel, wherein the first and second interlocking profiles permit sliding interconnection of the first and second rails along the rail profile axis with the retention channel in the second rail oriented perpendicular to the rail profile axis, wherein the bicycle accessory is connected to the second rail;
• a clamp bar having a longitudinal axis perpendicular to the rail profile axis, wherein the clamp bar is sized to slide freely perpendicular to the longitudinal axis of the clamp bar between the first end and the second end of the opened channel in the first rail and, when the first rail and second rail are interconnected, to slide freely perpendicular to the longitudinal axis of the clamp bar between a first position beyond the top surface of the second rail and completely outside the retention channel in the second rail to allow the second rail to slide freely within the first rail and a second position below the top surface of the second rail and within the retention channel in the second rail to lock the second rail within the first rail;
• and
• a tension applying device configured to apply tension to the clamp bar to squeeze the first interlocking profile of the first rail onto the second interlocking profile of the second rail when the clamp bar is positioned within the retention channel.