A flexible tool includes an optical fiber including a proximal end, a distal end, an intermediate portion between the proximal end and the distal end and an adjustable bend between the proximal end and the intermediate portion. The intermediate portion may be constrained to have a single degree of freedom that is translational substantially along an axis defined by the optical fiber at the intermediate portion. The adjustable bend may be enclosed with a housing that provides space within the housing for the adjustable bend to adjust. The optical fiber may be used to provide shape sensing of the flexible tool.