Hi!

The Silkroad was (partly still is) a network of roads, not a single track.

Sofar there is not not a gps route yet. I will cycle the route this year starting in May. I will cycle through Turkey, Iran, Turkmenistan, Uzbekistan, Tadzjikistan (Pamir) to China (Kashi) and then Tibet and further and I will track the route with my gps. The part between Istanbul and Kashi can be seen as part of the Silk Road network.

For Tibet (Kashi-Saga) I just finished a google earth trackfile (*.kml) using roadbookdata. To get an idea look here.
I will have finished the whole route through Tibet later this week. If you like you can fly the route but it takes a long time

Cycle the world (with GPS for tracking),
Marc