Positive and negative force crankset for bicycle

The utility model discloses a positive and negative force application chain wheel for a bicycle. The chain wheel comprises a chain wheel assembly, the crankset assembly is arranged on a bicycle middleshaft. Center shaft arranged on frame, the crankset assembly is connected with a gear set arranged on a rear wheel axle through a chain. The chain is arranged on the derailleur; the derailleur is arranged on the frame; the crankset assembly comprises a center gear, a forward force application gear, a fixed disc, a gear sleeve, a planetary gear and a reverse force application gear. A connecting flange is arranged on the forward force applying gear; a central gear is arranged on the connecting flange; the central gear is meshed with the planetary gears; the planetary gears are evenly distributed on the fixed disc, the fixed disc is arranged on the middle shaft in a sleeving mode, the planetary gears are meshed with the gear sleeve, the gear sleeve is arranged between the forward force application crankset and the r