A system of devices facilitate the uninterrupted transport of a payload of persons (110) or cargo along a guide cable (180), or zip line, suspended from at least two support structures (120). Transfer mechanisms (800, 810) allow the cable to loop to a starting location or to transport between discrete endpoints. A trolley (200) carrying the payload may be powered by gravity alone, or a motorized assist may allow the cable course to be traversed without regard to relative elevations of cable supports. A motor may serve as a regenerative speed governor or braking device to charge a power supply for travel against gravity. The system enables one or more riders (110) to travel along the guide cable (180) at velocities desired for recreational purposes while assuming many body positions, such as prone, sitting or standing, to provide the sensation of flying like a bird.