Contact point foot-pedal
There are two reasons why the pedals as points of contact are of interest for a biomechanical analysis. First, it is worth knowing how strongly the foot is strained when pedalling in order to prevent eventual pain from occurring. Second, this is the point of contact that is responsible for the crank’s movement and accordingly for the thrust of the whole bike.
Just as for running shoes, insoles have probably the largest effect on the pressure distribution. By slightly lifting the area of the foot’s longitudinal arch or by lifting the retro-capital region (the area between the foot’s ball and longitudinal arch) partly pressure values can be reduced, because the load is distributed over a larger area. The better the insole is fitted to the rider’s foot and his needs, the better is the load situation for the foot.
When pedalling there is a pushing phase, lasting from the upper to the lower pedal position – assuming roughly . During this phase the maximal power is transmitted to the pedals. In the subsequent pulling phase, lasting from the lower to the upper crank position – again assuming roughly, the interaction power between foot and pedal is low. In the best-case scenario negative power is possible referring to a real pull on the pedals. However, the measurements conducted so far have revealed that few riders are able to generate such a pull in practice. It is obvious that the phases of pushing and pulling are contrary for the left and the right foot – while the former pushes the latter pulls and vice versa. It is the sum of the forces of the two feet at each moment in time that determines the thrust.
The parameters cadence and force can be used to determine the rider’s power. Over a longer period this determines the average speed achieved over the distance ridden. The performance can be enhanced by increasing the force on the pedals or by increasing the pedalling frequency.
A major shortcoming of the conventional systems employed for performance diagnostics is their inability to break the total power down for the left and right foot respectively. The development of such a measuring system and the corresponding software allowing the left/right differentiation under realistic circumstances is an important task for the near future. This would make left/right comparisons concerning the symmetry of pedalling possible and so it could be used to enhance round pedalling.