An idler wheel support for a conveyor belt comprises a gear rack adjustment mechanism or for use in adjusting the position of one end portion an idler wheel supporting frame. The gear rack is provided at said one end portion of the frame, such as on a foot, or on a base to which the foot is slidably coupled. A tool comprising a gear is selectively positioned for pivoting on the foot or base that does not have the gear rack with the gear engaged with the gear rack. When so engaged, pivoting the gear shifts said one end portion of the frame and adjusts the angle of the frame relative to the longitudinal conveyor frame axis and adjusts the longitudinal tracking of the conveyor belt. The gear can be mounted on a lever and positioned for pivotal engagement with the gear rack to enable adjustment of the belt tracking while the belt is moving.