An optimal explicit force control scheme for flexible link manipulators is considered in this article. The control output is composed of a feedforward and a feedback term. The feedforward torque component compensates the underlying rigid arm dynamics along the desired trajectory. The feedback component regulates perturbations to the linearized rigid body output error dynamics. The minimization of a linear quadratic frequency-shaped cost functional yields the feedback controller gains. The frequency shaping dependence is included to eliminate undesirable effects associated with control and observation spillover. Sufficient conditions for spatial tracking bounds and temporal gain switching bounds for the linearized error dynamics are provided. The proposed control scheme is applied in simulation studies on a two link rigid-flexible manipulator.