Fiber-reinforced elastomeric bearings were originally proposed as an alternative to conventional steel-reinforced elastomeric bearings for seismic isolation applications. The flexible fiber reinforcement is a light-weight and potentially cost saving alternative to steel reinforcement which is assumed rigid in the design process. The variety of fiber materials available also serves as an additional parameter for designers to tailor the vertical stiffness of the bearing. In this paper, the analytical solution for the vertical compression modulus of a rectangular elastomeric pad including the effects of bulk compressibility and extensibility of the fiber reinforcement is used to investigate the achievable decrease in vertical frequency. It is shown by an example that the extensibility of the fiber reinforcement can be used to significantly reduce the vertical stiffness in comparison to an equivalent steel-reinforced elastomeric bearing. The resulting decrease in the vertical frequency means that fiber-reinforced elastomeric bearings may have an advantage over steel-reinforced bearings in the vibration isolation of buildings.