A shape sensing enabled instrument includes a flexible longitudinal body (103) including an outer surface which encapsulates interior features. The interior features include an optical fiber lumen (105) configured to receive one or more optical fibers for optical shape sensing, and a mechanical member (107) forming a hollow extending longitudinally down the body. The mechanical member is configured to receive the optical fiber lumen therein to permit rotation and translation of an optical fiber and to protect the optical fiber.