A certain biomechanical model involves ordinary differential equations. This research focuses on solving a biomechanical model of a cyclist coasting downhill. The objective of this study is to establish the velocity of the model, using two numerical methods, i.e., the third-order Runge-Kutta methods. The two methods are the existing classical Runge-Kutta and a modified Runge-Kutta method formed by Wazwaz. The numerical results obtained from these two methods are compared with the exact solution and the relative errors are produced.