The optimization of the cyclist's position aims to increase performance and may prevent injuries. To find the optimum posture, taking into account anthropometry of the cyclist is essential [1] because an anatomic asymmetry (short leg) could alter the cyclist's balance causing a decrease of power output for one of the two lower limbs. Bilateral pedalling asymmetry may amplify the risk of premature fatigue and injuries [2]. Biomechanical foot orthotics (FO) are used to reduce injuries [3] and to increase performance [4] improving left/right balance between the two legs. The aim of this study was to analyse the effect of the installation of a new FO (just after the laying) on a bilateral pedalling asymmetry in cyclist affected by an anatomic asymmetry (short leg).