The present application provides external bone fixation systems. The systems include one or more pairs of bone fixation platforms in the form of rings or partial rings. The platforms may be coupled to corresponding bone segments. The pair of platforms are configured to accept a plurality of struts extending therebetween. The struts are configured to attach to the platforms via joints that provide three degrees of rotation. The struts are also configured such that their longitudinal length extending between the joints/platforms can be incrementally adjusted while attached to the platforms. The struts are further configured such that their total range of length adjustment can be increased by coupling at least one add-on component to the struts in situ. The lengths of each of the plurality of struts may be adjusted to arrange the platforms, and thereby the bone segment coupled thereto, in particular relative positions and orientations.