An implantable drug infusion device includes a pump tube for holding a liquid to be pumped. A race is configured to support the pump tube. A roller assembly is configured to compress the tube against the race at one or more points along the path, and the roller assembly includes at least one roller and a hub. A drive assembly drives the roller assembly relative to the tube along the path so as to move the liquid through the tube. A retracting roller is operably connected to the hub and/or one or more adjacent rollers to permit retraction of the roller during installation of the pump tube between the roller and the race.