Spock has never ridden a bicycle. Two-wheeled, self-propelled vehicles were never invented on Vulcan, as the sand is difficult to maneuver through without feet or treads. This fact is revealed when they must conduct an away mission on a planet which primarily uses bicycles for transportation. He finds the humans’ nostalgia over the little wheeled-metal-things to be quite interesting, if illogical. He expects his Vulcan poise, strength, and agility will allow him to easily master bicycle riding–but he is very mistaken. He skins both his knees before the rest of the away team realizes he’s never done this before. They instruct him on what to do, and manage to find one training wheel for him, and Captain Kirk runs alongside him pushing the bike to help him get going. Spock finds the wind in his hair to be surprisingly exhilarating, and when he turns to share this with the Captain he finds Kirk is no longer running beside him. He’s biking all on his own.