Thanks, huey, but I'm still puzzled. Seems that if I ever needed to replace cables, I could reverse the process (slip on sheaths, remove old cables, route new cables, remove sheaths). My question is, after installation, do i remove the sheaths, or simply keep them in place? It seems that it would be easiest just to leave them there, but then other concerns arise; namely, how do I cut the sheaths so that 1) the sheath butts up against the exterior cable housing at the point of entry, and 2) how do i avoid cutting the sheaths so short that they fall into the frame?

If I ever buy another frame, it's going to have external cables. Period