Bicycle square-head center shaft structure with bearings

The invention relates to a bicycle square-head center shaft structure with bearings. The bicycle square-head center shaft structure is characterized by being composed of a center shaft, a limiting bottom bracket with a boss in an inner cavity, a gasket, a dustproof cover, a retaining pad, locking nuts, a bicycle right crank, crank locking nuts, pedals, a chain wheel, the bearings and a bicycle left crank. The center shaft is provided with the limiting bottom bracket with the boss in the inner cavity, the gasket and the dustproof cover, the two bearings and the retaining pad are arranged in the center shaft, fastening connection is achieved for the two ends of the center shaft through the locking nuts, the bicycle left crank is arranged at the left end of a square head of the center shaft, the bicycle right crank and the chain wheel are arranged at the right end of the square head of the center shaft, fastening connection is achieved for the cranks through the crank locking nuts, and the pedals are arranged at