A cable in suspension (clear span) supports a trolley. At the upper end, a launch block fixed to the cable registers the trolley in all directions, including a safety release link holding the trolley near the launch block. After release and descent with a rider, the trolley strikes an attenuator of distributed springs and spacers. The spring stack absorbs momentum from the trolley, but a leash limits recoil “bounce” after reversing the trolley. A second, recoil, leash resists recoil by capturing a subset of the springs between respective ends of itself and the first leash. The doubly leashed trolley will oscillate to a stop in an equilibrium position.