This paper proposes a novel method for generating a dynamic gait based on anterior-posterior asymmetric impact posture tilting the robot’s center of mass forwards. The primary purpose of this method is to make the impact posture become asymmetrical by actuating the robot’s telescopic legs to easily overcome the potential barrier at mid-stance, accordingly restoring the mechanical energy. First, we introduce a planar rimless wheel model with telescopic legs, and investigate the validity of the stance-leg extension control. The basic properties and efficiency of the generated gait are also numerically analyzed. Second, we extend the method to a planar telescopic-legged biped model, and investigate the validity through numerical simulations. We also discuss the role of asymmetric shape of human foot through efficiency analysis from the point of view of the brake effect, taking the ankle-joint actuation into account.