Several weeks ago, a friend of mine was leading a pace line in a charity bike ride. He was in front of 10 other riders and was going 22 miles an hour. Everything seemed fine until his handlebar snapped in half and he lost control of his bicycle! Needless to say he was seriously hurt. At this point, we're not sure what caused the failure. It could be a defect in manufacturing, age of the part, or a mistake made in the installation that caused fatigue and ultimate breakage.
One thing is certain, when you are on a bicycle, the smallest little failure can cause the biggest disaster.
Everytime you ride at a minimum you should check your tires, brakes and look for signs of wear and tear on the frame and components.
It's better to have a fence at the top of the hill than an ambulance in the valley below.