A rower exerciser includes a frame which is disposed on the floor to serve as a supporting frame, a slide rail connected between front end rear ends of the frame, and a slide seat slidably mounted on the rail to slidably reciprocate along the rail and being adapted for sitting by the user. The release graduating proportioning valve has a proportioning piston movable between a first position at which a control volume is isolated from atmosphere to a second position at which the control volume is connected to atmosphere, to enable graduated release of brake cylinder pressure. Following extrusion, the frame profile may be stored, cut, trimmed, cure, etc.