4. Motorcycle Kings

At the end of the 19th century, private travel means taking a walk or riding a horse. But scrappy upstarts William Harley and Arthur Davidson have a bold vision for a new form of transportation--connecting a motor to a bicycle. They'll take on George Hendee's Indian Motorcycle in a classic David Vs. Goliath battle, fighting to dominate a market valued at more than 7 billion dollars today, the rivals will push their machines to the limit and tap into the lure of the open road.