The Hoop Hole Trails are unique. You’ll definitely feel like you are off the beaten path out here. I’ve mapped out a couple options for you depending on what you are looking for. You’ll get both climbing and some technical trail here.
Small option is around 3-4 miles. I’d recommend doing this loop counter clockwise.
Medium option is around 9 miles and would again recommend going in a counter clockwise direction. The upper loop would be good in either direction but I think finishing up by coming down the west side of the lower loop, through the rhododendrons would be a icing on the cake.
Here is a Garmin link for the medium option – https://connect.garmin.com/modern/activity/2161156650
Large option is around 14 miles. To do this option you would park at Roaring Run and do the Iron Ore trail to get to the Hoop Hole loops. From here you also have the benefit of checking out roaring run.
Getting there: Take I-81 Exit 150 (a few miles north of Roanoke), drive US 220 north for 20.5 miles, turn left onto VA 615, and make a right into the parking area in another 7.8 miles. You’ll pass the turn off for Roaring Run on your way to the Hoop Hole parking lot.