A backpack frame comprises side rails defining a first profile. The first profile has a flat first base segment lying on a first reference plane, and a first concave segment leading from the first base segment to an upper end of the frame, with the first concave segment being spaced a maximum distance from the first reference plane at a first location between the first base segment and the upper end of the frame. An intermediate structure interconnects the side rails. The intermediate structure defines a second profile having a second flat base segment lying on a second reference plane parallel to the first reference plane, and a second concave segment leading from the second base segment to the upper end of the frame, with the second concave segment being spaced a maximum distance from the second reference plane at a second location between the second base segment and the upper end of the frame. The first and second locations are offset from one another.