Dr. Pruitt, U.S. biomechanics, has placed its focus on the determination of the saddle height so that the knee joint can work without stress on the tendon-cartilage structures.
Putting his foot on the pedal in a horizontal position, parallel to the ground, and with vertical crank down (bottom dead center) is the angle between the femur and the tibia must be extended to a maximum of 25-30 degrees. In this static situation would then correspond, in the dynamics of pedaling, an angle of 40-45 degrees due to the extension of the ankle.
Is not a popular method and does not lead to improved efficiency biomechanics of pedalling (at least according to some experts) as upper position the seat. But it's a very good system because it allows to minimize the possibility of disease at the knee and takes into account their shoes and pedals used. The main problem is the correct definition of the angle of the knee work, because the static measurements may differ considerably from the dynamics, it should then compare the two different measurements, which is not very easy to achieve. Overcome this obstacle remains among the best systems of regulation of the saddle so as to minimize the trauma to the knee.
Dr. Haushalter reached conclusions similar to those of Dr. Pruitt. Analyzing the working angles of the knee has led to a height of the saddle that leads to a good biomechanical efficiency, but to avoid unnecessary trauma and overload the knee. Positioning the crank at bottom dead center with the heel down to the level of the axis of the pedal or slightly below the angle formed by a line joining the lateral malleolus to the head of the fibula and the vertical line that descends from the same femoral head should be 15 degrees. The height of the seat must be adjusted so that you create this angle.
Like the method Pruitt, Haushalter emphasizes the need for the ride does not lead, in the long term, trauma and injuries to the knee. The height of the saddle is higher than all other methods and, in practice, coinciding with the method Pruitt, of which it is common strengths and weaknesses. Among the merits of the possibility of reducing trauma to the knee, the adjustment based on the shoes and pedals adopted, the analysis of flexible muscles and joints. The defects, in addition to reduced biomechanical efficiency, the difficulty in determining the correct working angle of the knee.