Asymptotics of nonstationary solutions to the Riemann problem are studied for a system of equations describing long small-amplitude longitudinal-torsional waves in nonlinear elastic rods in the presence of dissipation. It is shown that the form of the asymptotics of the solution depends on the dissipation parameters. The asymptotics of a nonstationary solution may correspond to theself-similar solution of the Riemann problem or, for other values of the dissipation parameters, may contain special (nonclassical) discontinuities.