A drive mechanism for a vacuum cleaner having a motor and an agitator includes a belt coupled to the motor and the agitator to drive the agitator, and a belt tensioner operable to selectively tension the belt. The belt tensioner includes an arm movable relative to the belt, a shaft coupled to the arm, a pulley rotatably coupled to the shaft, a bearing positioned substantially within the pulley and around a portion of the shaft, and a member fixed to the pulley to retain the bearing within the pulley.