A bicycle wheel rim includes spaced left and right annular tire retaining walls adapted for retaining a bicycle tire therebetween. Each of the tire retaining walls has a central axis, a radial inner edge proximate to the central axis, a radial outer edge distal to the central axis, and a brake pad contacting surface opposite to the other one of the tire retaining walls. An annular spoke mounting wall interconnects the radial inner edges of the tire retaining walls. The brake pad contacting surface of at least one of the tire retaining walls is formed with a plurality of radial grooves which are spaced apart from each other in a circumferential direction relative to the central axis and which extend along radial directions of the tire retaining walls from the radial inner edge to the radial outer edge. Each of the radial grooves has at least two opposite open ends formed respectively through the radial inner and radial outer edges.