The front light runs in and out of holes on the inside of the fork leg. To route the rear light, locate the hole on the bottom side at the upper portion of the down tube behind the head tube. The wire enters there, and once the fork is removed, can be routed through the head tube and into the top tube where it runs the length of the frame before exiting at the plug just before the seat tube. There isn't an external option unless you want to make up your own with the brake hose/rear shifter cable.