Comparison of static and dynamic methods based on knee kinematics to determine optimal saddle height in cycling.

Purpose: Bike-fitting methods based on knee kinematics have been proposed to determine optimal saddle height. The Holmes method recommends that knee angle be between 25° and 35° when the pedal is at bottom dead centre in static. Other authors advocate knee angle of 30-40° during maximum knee extension while pedalling. Although knee angle would be 5-10° greater at bottom dead centre during pedalling, no study has reported reference values in this condition. The purpose of this study was to compare these three methodologies on knee, hip, and ankle angles and to develop new dynamic reference range at bottom dead centre.

Methods: Twenty-six cyclists volunteered for this experiment and performed a pedalling test on their personal road or mountain bike. Knee, hip, and ankle angles were assessed by two-dimensional video analysis.

Results: Dynamic knee angle was 8° significantly greater than static knee angle when the pedal was at bottom dead centre. Moreover, dynamic knee angle with the pedal at bottom dead centre was 3° significantly greater than dynamic knee angle during maximum knee extension. The chosen methodology also significantly impacted hip and ankle angles under most conditions.

Conclusions: The results allow us to suggest a new range of 33-43° when the pedal is at bottom dead centre during pedalling. Thus, this study defines clearly the different ranges to determine optimal saddle height in cycling according to the condition of measurement. These findings are important for researchers and bike-fitting professionals to avoid saddle height adjustment errors that can affect cyclists' health and performance.