Abstract: A physical climbing apparatus having a sprocket carrier frame structure includes first and second carrier members supported in parallel relation. The frame is made up of members which are extensible. This allows the frame to be supported at selected inclinations. It also allows the apparatus to be collapsed to a substantially flat position for storage and shipping. A pair of rotatable idler sprockets support each chain from deflection caused by a person's weight. The idler sprockets locate closer to the lower end than the upper end and engage a forward run of the chain. A hydraulic rotation control system adjustably controls the rate of rotation of the sprockets.