The numbers of deaths and seriously injured citizens prove that traffic accidents and their consequences are still a serious problem to be solved. Virtual human body models play an important role to assess injuries during impact loading. The most suffering group is so called vulnerable road users like pedestrian, cyclist and two-wheeler (TW) riders, where complex dynamical loading is taken into account. The presented work contributes to the virtual approach towards TW personal protective equipment (PPE) optimization. Since optimization process concerns running plenty of simulations, multi-body system (MBS) for human body modelling is convenient to save calculation time. However, the PPE must be usually modelled as the full finite element (FE) system, because of the proper behavior and energy absorption. Helmet is one of the most protective part and it usually accommodates complex materials to ensure impact energy absorption and influence the head/neck complex kinematics. If helmet optimization is not the issue, helmet might be simplified for calculation, but with the same performance of the whole head/helmet system. The current work couples existing scalable hybrid human body Virthuman to simple helmet by extending the MBS by adding the helmet as an additional rigid body. The head is linked to the helmet by 3D spring. The 3D spring properties are developed based on impacts of the full FE helmet model coupled to head in all major impact directions using several velocity levels. The whole helmet/human multibody system is validated in oblique impact scenarios for head acceleration. The numerical study shows that the simplified helmet model linked to the human MBS as an additional rigid body has the same performance by considerably decreased calculation time.