An axle/suspension system for a heavy-duty vehicle, in which the vehicle includes a frame that extends in a longitudinal direction relative to the vehicle. The axle/suspension system is attached to the vehicle frame via at least one hanger and includes at least one beam, which includes a first end and a second end. The first end of the beam is connected to the hanger, and the second end of the beam immovably captures an axle, which extends in a transverse direction relative to the vehicle. The beam is formed of a composite material and has a substantially constant cross section in the transverse direction to provide sufficient strength to control roll forces encountered by the vehicle during operation.