Bicycle with suspension device

This invention relates to a bicycle with a suspension device, comprising a main-frame having a substantially triangular connected front tube, an upper tube formed by the backward extension of the front tube, a slanted, downward extending down tube disposed below the upper tube, and a seat tube disposed in an interval to the front tube fro connecting the upper tube and the down tube, wherein an vertical aperture is formed on the down tube. The suspension device, passing through the aperture, is pivoted between the main frame and a sub-frame for buffering and bearing the force produced by the motion of the sub-frame. When moving over an obstacle, the suspension device may absorb the vibration and shock from the sub-frame so as to provide a more comfortable riding experience. Therefore, this invention may enhance the operability of a bike and provide a more desirable shock-absorbing characteristic.