A low-friction medical device is provided having roller-assisted tension members and a friction-reducing curved guide path. The device includes a first link, a second link, and a tension member. A proximal end portion of the first link is coupled to an instrument shaft. A proximal end portion of the second link is rotatably coupled to a distal end portion of first link about a first axis. The second link defines a curved guide path and a cable extends from the first link through the curved guide path to a distal end of the second link and couples with a tool member. A roller having a roller surface is coupled to the second link such that the roller surface is aligned with a portion of the curved path and contacts the cable therein. The curved guide surface has a small fleet angle.