The frame is the most important part of a bike since it supports the rider and all of the other components of the bicycle. The geometry and design of the frame largely determines the intended use of a bike. There are high demands on the quality of a bicycle frame. It should be both solidly built and lightweight. That is why the choice of material plays an essential role. Bicycle frames are commonly available in aluminium and carbon. The most popular frame design is known as the diamond or double-triangle frame. The strength of the design comes from the triangle shapes that make up the diamond design.