A tensioning tool device includes a flexible or spring support having a spring bearing that translates a linearly applied external force at an input to linear displacement at an output of the spring bearing. An external force applied to the input of the spring bearing causes the output to pull on a section of the optical fiber and imparts axial strain and tension in the optical fiber. The spring bearing includes one or more sets of parallel flexible beams cantilever-coupled to the input and output, to provide a flexible/spring structure that couples an external force input to an output coupled to the first section of the optical fiber. The external force is applied to displace the input to flex the fixed-guided beam(s) to impart axial tension in the optical fiber at the output of the flexible bearing.