Abstract: A bicycle includes a notch centrally defined therein and two support portions respectively formed on two opposite edges of the notch, wherein each support portion complementally corresponds to lateral nipples. The bottom of the notch is divided into a first inclined face and a second inclined face. Each inclined face has a series of first through holes equally and vertically defined therein such that each first through hole has an axis forming an angle with a corresponding one of the diameters of the bicycle rim, wherein the first through holes in the first inclined face are interlaced to that in the second inclined face.