A rim (1) for a bicycle wheel, having a body (5) with a substantially annular extension and a radially outer portion (6a) shaped for coupling with a tire is disclosed. The radially outer portion (6a) includes an annular bottom wall (12) provided with a hole for an inflation valve, and the annular bottom wall (12) defines a central annular recess (20) and two side annular portions (24) arranged on axially opposite sides with respect to the central annular recess (20). The recess (20) includes, on at least one side, and in at least one circumferentially distal area from the hole with reference to a cross section of the rim (1), a radially inner surface (26) and a radially outer surface (28). The radially outer surface (28) has a different bending radius than that of the radially inner surface (26).