I used "Cobra Flexroute" (Flexroute Cable Management Solution - Cobra Cable Ties | Cobra Products) and some carbon fiber tubing used for model airplanes I picked up from the hobby shop (I think it was 3/16" od). The wire fit snugly inside and doesn't rattle around. It worked out real good and is very discreet. For a vintage bike, I would of probably used the cable route rings and polished some aluminum tubing, but it's on a modern bike, so really not much an issue.