Abstract: A device for retaining a mobile device on exercise equipment without screws or tape and gravity alone. The retaining device may include a platform for accessibly supporting the smart device along an upper surface of the platform. The upper surface provides a sliding shelf that can be selectively secured to different locations along a longitudinal axis of the platform. A lower surface of the platform may provide spaced apart rearward and forward notches for removably securing the platform to one of various exercise equipment, wherein the forward notches are selectively exchangeable and the rearward notch has large radius of curvature to substantially engage more planar portions of the exercise equipment.