a unicycle.his bike may look like something out of the circus, but there's a group of people who are devoted to riding it. >> favorite part about unicycling is that it's different from other sports and it's really fun to learn new tricks. >> probably the...adrenaline, like, when you ride, and the balance techniques. >> my favorite part about unicycling is when, if you're riding around town, is people notice you and they talk about you and you feel special. >> so, i guess, what is this group that you have? >> this is the new york unicycle club. i founded it, along with a friend and my brother, back in 2001. >> now david's group has over 300 members, both young and young at heart. most historians believe the unicycle was created in the late 1800s, when a contraption called the penny-farthing boomed in popularity. the penny-farthing was named after two british coins. its big front wheel looked like a penny, and its small back wheel looked like a farthing. but it wasn't long before riders realized th