This paper addresses the design of active controllers for enhancing the stability properties of two-wheeled vehicles, which are not yet available on neither commercial nor racing vehicles. To address this problem an active steering damper is employed by means of which the yaw rate of the vehicle is regulated with a switched, second order sliding mode controller. The switching mechanism allows us to cope with the possibly time-varying uncertainties that affect the system by adapting the control gain. The switching is time-based and it does not require additional measurements or estimators to perform the adaptation. Simulations are carried out on a model of the vehicle lateral dynamics witnessing the advancement enabled by the proposed approach with respect to other existing solutions.