dunno where you are coming in from but you can hit 16 in tazwell va and ride the 3 mountains down to marion, then ride down from exit 45 to exit 19 and go to damascus on 58 and then hit 133 (i think) towards backbone rock and then when you get the crossroads at US 421 you can go about 10 miles...
I live a few miles from US 421 (Bristol, TN/VA) and am usually at my girl's house in Wytheville, VA on the weekends.
I'm up for riding the 5 state area if anyone is organizing rides.