The relative terminal rising velocity of a single gas bubble, moving into a liquid phase, is determined by its size, by the interfacial tension, by the density and viscosity of the surrounding liquid. Both shape and velocity are strongly interacting. Along the years several methods have been presented for solving the problem of bubble deformation and relative rising velocity, at least in connection with some specific regimes of motion and/or share of bubble. In this work, a new approach is proposed,