The average bicycle is around 68 inches long, including the wheels. A bike's length depends on the size of the wheels and the wheelbase of the bike. The wheelbase is around 39 to 42 inches on most bikes, and most wheels are 26 to 29 inches in diameter.
The wheelbase is not considered important when sizing a bicycle. Bicycles are instead sold by frame size, which is the height of the frame's seat tube. Another factor to consider when buying a bicycle of the correct size is the length of the rider's leg, called the inseam measurement. The length of the top tube on the frame, which defines the distance between the seat and the handlebars, is also important to consider.