Abstract: A wheel rim for a bicycle includes an annular slot formed between two peripheral sides each having a number of grooves formed in the outer surface and formed between a number of concentric ribs which are used for engaging with a brake pad. The outer surfaces of the wheel rim each includes a wavy shape. The ribs are preferably tooth-shaped. The wheel rim includes two or more concentric bulges formed between the ribs and having a height greater than that of the concentric ribs for engaging with the brake pad and for facilitating the braking operation of the bicycle.