WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

Do you know how to ride a bike? Great! It's a lot of fun. When you first learned to ride, did you fall a lot? When people are learning to ride a bike, they often make big, jerky movements with the handlebars wheel and their bodies. The bike falls over, and they end up with bruises and scrapes. 

Falling happens because of gravity (GRA-vih-tee). Gravity on Earth pulls things toward the center of the planet. It’s why your bicycle will fall down when you’re riding it unless the weight on one side is the same as the weight on the other side. When the weight is equal on both sides, the bike is balanced. When a bike falls over while you’re riding, you have lost your balance. As you get more practice riding your bike, this happens less and less. 

To balance on your bicycle, your brain and your muscles must work together. That’s called coordination (co-or-di-NAY-shun). When you feel the bicycle going too far to the left, you move your body and the handlebars to the left to keep the weight balanced. When the bicycle goes too far right, you move right. It sounds backwards, but you have to turn into the fall. That keeps the front wheel of the bike underneath you. And that keeps you from falling!   

There’s a special part of your brain that handles this: the cerebellum (ser-eh-BELL-um). It's located at the back of your brain. Your cerebellum controls your coordination and balance, and it controls when you move your body. With a little practice riding a bicycle, your cerebellum will help your body move just the right amount at the right time so that you can balance on the bike without having to think about it at all. 

To see a wacky experiment about riding a "backwards brain bicycle," watch this video from Smarter Every Day. And for more cool facts about the cerebellum and other parts of your brain, visit KidsHealth