Height of the Saddle – Knee Pain & Energy Consumption

The assembly of the bicycle is an important process to fit the geometry of the bike to the needs of each rider. Ideal position for pedaling one is that which maximizes the output power and comfort while minimizing the forces of resistance and the risk of injury. During that assembly, perhaps the most important parameter is the height of the saddle  (Fonda et al 2014).

 

   An improper adjustment of saddle height will result in an excessive load of the knee joint (Ericson and Nisell 1987) and increase the consumption of oxygen and thus to rapid fatigue (Price and Donne1997).

    Setting the correct saddle height is important because it affects the total force exerted on the pedal and hence the production of work . It is obvious  even to the most inexperienced rider that a higher seat position (relative to a lower ) increases the power and energy consumption in the same way that, one climbs easier one by one  the rungs of a ladder rather than two or three together (Baker 2009).

The most common method of adjusting the saddle height is shown in Figure.1

FIG. 1 A saddle height (measured in the manner shown in the figure) that lead to a

 30 °  flexion in the knee joint fits to the most riders. (shown in red benchmarks: from top to bottom, the greater trochanter, the  lateral femoral condyle and  the lateral malleolus).

   Fitting  the saddle  too low causes knee pain, either in front of the joint, or in the inner part of the joint. The pain that occurs in front of the knee joint is the most commonly reported injury derived from repeated wrong forces  to the joint . The low seat position will lead to diversification of allocation of the forces in the knee joint and the attendant problems we mentioned. The higher than normal seat position will lead to pain in the back of the knee and the outer part of the joint , and to  hamstrings and Achilles tendon problems.

    This classic method for measuring the angle of the knee sometimes depends on the need of each cyclist to change. For example, many cyclists,  when they increase the speed, they come forward, increasing the knee flexion , and professional cyclists often prefer a little lower sadle  position, which help them keep balance, when pedaling hard in big parts of the route (Baker 2009).

   The study of Salai et al (1999) had been proposed an additional anterior inclination  of the  saddle 10^ο -15^ο   ( FIG. 2 ) in odrer to avoid problems in the spine and low back pain.

  FIG.2   Anterior inclination of the saddle 10^ο -15^ο   

   The results of  the  Connick and Li research (2012),  shows that a change in saddle height modifies the proprioceptive biofeedback and thus used in professional cycling athletes to accurately determine the timing of  the eccentric contractions of the hip muscles. On the other hand,  a change of saddle height by ± 4% compared with the height of the great  trochanter of the hip,  do not change the energy consumption  of the cyclist.

                                                  Haralambakis   Haralambos

                                                           Physiotherapist 

Sources:

1) Baker Arnie (2009)  Bike fit,  Argo Publising,  Canada

2) Connick, Mark J. and Li, François-Xavier (2012) The impact of altered task mechanics on timing and duration of eccentric bi-articular muscle contractions during cycling. Journal of Electromyography and Kinesiology, 23 1: 223-229.

3) Ericson, M., & Nisell, R. (1987). Patellofemoral joint forces during ergometer cycling. Physical Therapy, 67, 1365-1369.

4) Fonda B., Sarabon N., Li F. (2014) Validity and reliabilityof different kinematicsmethods using for bike fitting. Journal of Sports Sciences Vol 32 No 10 940-946.

5) Price, D. and Donne, B. (1997) Effect of variation in seat tube angle at different seat heights on submaximal cycling performance in man Journal of  Sports Sciences 15: 395-402