This article introduces a simple and fast method to reinsert atomistic details into mesoscale models of polymers with rigid side groups. We describe our backmapping scheme from a coarse-grained (CG) resolution to an atomistic picture in the framework of molecular dynamics (MD) simulations of a silica-atactic polystyrene (PS) composite. The CG model of Qian et al. [Macromolecules 2008,41,9919] has been used in the coarse-graining; it combines the atoms of one repeat unit of PS to a CG bead. In the reverse mapping only the centers of mass of these units and their chiralities are known. We show that this information is sufficient for the reverse mapping which requires simple geometrical and mechanical considerations. The capability of the suggested method is demonstrated by comparing MD results from the original atomistic model with those emerging from the reverse mapping. Because of its simplicity, the suggested technique offers the opportunity to study relaxed structures of melt chains with large molecular weights.