An assembly for installing an optical fiber cable which includes a fiber core assembly and a reinforcement yarn assembly surrounding the fiber core assembly. The assembly includes a leading unit having a yarn positioner for fixing a front part of the reinforcement yarn assembly, and a trailing unit including a front cap, a rear tube, and a middle tube that has front and rear threaded portions threadedly engage the front cap and the rear tube, respectively. The front cap has a threaded sleeve portion sleeving around the front threaded portion of the middle tube for clamping a rear part of the reinforcement yarn assembly against the middle tube, thereby fixing the rear part of the reinforcement yarn assembly.