For high-functional mobility or assistive platforms for personal users, development of bearing hub units capable of not only achieving enough large load bearing capability but also embedded sensory function especially for forces acting on it is crucial. For satisfying this requirement, this paper proposes a hub unit which basic concept has inspired from the composition of back-to-back arrangement angular-bearings. Thanks to this composition, the proposed hub unit can support a rotary shaft while it is freely revolving. In addition, the hub unit is designed to establish an embedded tri-axis force sensor function by separating an intermediate ring between upper- and lower layer rolling balls into several sections and connecting them by flexure hinges so that the internal and out-of-plane forces exerted from the shaft can be measured. The paper explains the concept and basic composition, then discusses actual design and simulation results demonstrating the feasibility of the concept.