Wear a bike helmet 
The Brutal Mechanics of a Bike Crash Will Convince You To Wear A Helmet
Bike wrecks happen fast. In two milliseconds—that’s one-hundred-times quicker than a blink of an eye—a regular ride can turn into a disastrous noggin-buster. If you ever doubted the importance of strapping on a helmet before you roll out, cycle giants Giro explain what happens to your head and the mechanics of a crash.
