A control device for a rear shock absorber of a bicycle, comprising:
- at least a first air chamber, a second air chamber, a third air chamber, an auxiliary air chamber, and a sliding rod;
- wherein:
- an interior of said first air chamber is filled with air;
- said first air chamber has an air piston arranged with a first air hole communicating with said auxiliary air chamber;
- an interior of said second air chamber is filled with air;
- said second air chamber is arranged with a second air hole communicating with said auxiliary air chamber;
- an interior of said third air chamber is filled with air;
- said third air chamber is arranged with a third air hole communicating with said auxiliary air chamber;
- said sliding rod is disposed inside said auxiliary air chamber and is provided with a first air tight ring, a second air tight ring and a third air tight ring arranged top-to-bottom;
- said first, second and third air tight rings tightly touch an inner wall of said auxiliary air chamber;
- a first groove is formed between said first air tight ring and said second air tight ring;
- a second groove is formed between said second air tight ring and said third air tight ring;
- said sliding rod is controlled by an adjusting unit to move axially in said auxiliary air chamber;
- said first groove manages said first and second air chambers to be disconnected or to communicate with each other by the axial movement of said sliding rod;
- said second groove manages said second and third air chambers to be disconnected or to communicate with each other by the axial movement of said sliding rod to adjust a damping coefficient of said air piston;
- said air piston fastened to one end of an oil chamber of an oil shock absorbing unit;
- said oil chamber, partitioned into a first oil chamber and a second oil chamber by an oil piston, is arranged with a shaft rod extending axially and inserted into said oil piston;
- said oil piston is arranged with a first through hole, a second through hole and a third through hole;
- said shaft rod relative to the bottom surface of said oil piston is configured with a small valve plate and a large valve plate;
- said small valve plate is pushed by the force of a large spring to block said first through hole of said oil piston;
- said large valve plate is pushed by the force of a small spring to block said second through hole of said oil pistons;
- said third through hole is not blocked by any valve plate;
- and
- said shaft rod is managed by a control device of a cam mechanism to adjust a position of axial movement with said shaft rod overcoming the spring forces from the large and small springs to drive said large and small valve plates to move to adjust said first through hole and said second through hole to close or to open, with the damping coefficient of said oil shock absorbing unit being adjusted.