Why is a racing bike much lighter than an ordinary bike, yet more durable? Why has the loading capability of a modern flight been increasing while the weight of the aircraft has been reduced? This is because more composite materials have been used in a racing bike, or in a modern airplane, instead of steel and other metallic materials. The reason that composite materials have high performance - materials such as glass fiber-reinforced plastic (GRP) and carbon fiber-reinforced plastic composites-is due to their structural complexity.