Disclosed is a load carrier (L) with an operating mechanism (6) for operating a clamp mechanism (1). The operating mechanism comprises a lever (7) pivotably supported on a support (9) about a pivot (P), a force application joint (73) connected to the lever, a force transmitting element (10) pivotably connected to the force application joint and pivotably connectable to an operated member of the clamp mechanism at a force application section (F) for applying a force on the operated member. A pivotal distance (d1) between the force application joint and the pivot is smaller than a pivotal distance (d2) between the force application joint and the force application section. In a tensioning position of the lever, the force application joint is positioned at a presettable distance (D) from the support. The operating mechanism further comprises an adjustment means for presetting the presettable distance between the force application joint and the support in order to adapt the tensioning force on the operated member.