The second analysis involved numerically determining the joint moments and push rim forces by imposing a purely tangent push rim force, i.e. by imposing a zero radial force, Fr = 0. This resulted in different joint moment profiles compared to the joint moment profiles determined in the first analysis, as shown on the left-hand side of Fig. 4. The right-hand side of Fig. 4 shows the estimated contribution of the inertial forces to the radial push rim component at different wheelchair velocities.