Two-flange spindle of bicycle

The utility model relates to an improved structure for a double-flange type shaft center of a bicycle. A main shaft is convexly provided with an annular step surface stopper facing to the basic part of the pushing and pulling surface beside a flange bead bowl, the step surface stopper is extended with a flat and straight section facing to the end, and the pushing and pulling surface is formed on the flat and straight section; the main shaft is connected with a four-angle cylinder by the flat and straight section, and a shim is sheathed on the flat and straight section of the main shaft, is butted on the step surface stopper, and extends out of the flange bead bowl about 1 mm. The shim can be used for providing a positioning reference surface when a fluted disc and a pedal rod are assembled so that the fluted disc and the pedal rod can not be moved inwards or deflected to contact the flange bead bowl.