Structural improvement of safety brake

This invention presents a structural improvement of safety brake, which is installed on a bicycle, motorcycle or other two-wheel linear-type vehicle, or another light vehicle with the left and right brake system to control the brake device in front and rear wheels. The characteristics are as: the ditch wheels of controlling the front and rear brakes are combined and placed, respectively; let the position of the ditch wheel of controlling the front brake be closer to the pivot point than the position of the ditch wheel of controlling the rear brake, to further generate the different brake forces and the working time difference; and, furthermore, the user can adjust the position of the ditch wheel following his own usual requirements by use of a position mechanism, to let when the brake system be controlled by one side of the left or right, or both sides, of the brake, the rear wheel will be braked firstly and then the front wheel is braked, so that the safety effect of that vehicle body is not easy to turn ove