"Biomechanics is the science that examines forces acting upon and within a biological structure and effects produced by such forces." (Nigg, B.M., Herzog, W.: Biomechanics of the musculo-skeletel system, Midsomer Norton, Avon, 1994, S.2)

Road Measurement

The sports scientific discipline of biomechanics deals with the interaction between human and material. With regard to cycling, biomechanics analyses the forces acting upon the bike, from within the rider and from the general environment. For doing so two aspects of force are especially important:
Weight, an external factor, is particularly relevant with regard to load, while the internal muscular forces (especially of the lower extremities) are responsible for the thrust. 
Generally, there are three points of contact in cycling where there is an interaction between the rider and the bike. These are the seat, the pedals and the handlebar. Whereas saddle and handlebar are important with regard to load, the connection between feet and pedals is essential for the performance. This shall be explained in the following paragraphs.