A Second Class Firecontrolman brought his bike and rollers with him on a fairly small guided missile frigate in 1987 and he used to ride it up on the fo'c'sle where the ship pitched up and down as wall as rolled from side to side. It was pretty easy, he let me do it as well. Having the visual reference frame of the ship's bow moving around was a little odd at first. Nice breeze up there as well. (Tech details: rollers oriented fore&aft just forward of the 5"54 gun mount on a Brook class FFG.)