From the Rock Creek Parking Area head northwest onto the Stanley Gap Trail #165
which is a typical north Georgia singletrack: red clay with a smattering of roots and rocks. It's heavily forested, so you won't have any sweeping views, but on the other hand, you've got some protection from the sun.
The climb is aerobically strenuous but not too technical although there are a few root-strewn sections that you'll just have to power through or walk around. The climb is nice in that after every 50-100 ft. of ascent there is a short, flat section that allows you to catch your breath a little.
The highest point on the trail is just below the summit of Rocky Mountain. There's a short descent and then one final climb before you reach a two-mile, 1,000 ft. descent. This descent begins at the point where the Benton MacKaye Trail breaks off to the north (unfortunately closed to bikes). The descent is filled with the same kind of roots and rocks that you encountered going up.
Take the Flat Creek Connector #165A
and turn right onto Flat Creek Loop #165B
. This trail is the easier version of its big brother, Stanley Gap Trail #165
. I'd recommend doing it in the shown counter-clockwise direction. The climb up to the highest point then is mostly a fairly wide, smooth singletrack and the grade is not as steep if climbing the other direction.
In the counter-clockwise direction then you've got the narrow singletrack with the roots and rocks to play on on the way down. It's a two-mile trip with 800 ft. of nearly continuous descent, and you'll encounter a half dozen or so unnamed creek crossings along the way. An intermediate rider should be able to ride all the way down.
The only downside to this trail is that once you reach the bottom, you've got about 400 ft. of climbing to get out of Flat Creek Valley and to the Deep Gap parking area.
From the Deep Gap parking area, cross Aska Road to the trail entrance on the east side. Here, the lightly twisting wide Green Mountain Trail #165D
begins a gentle ascent of Green Mountain.
Take the Long Branch Connector #165F
and turn left onto Long Branch Loop #165G
and ride the one-mile descent to the Shady Fall parking area. Ride across Shady Falls parking area and turn right onto Shady Fall Rd, then left on pavement, and ride south along Aska Road.
A short diversion onto Flat Creek River Road avoids a small segment of Aska Road. After 2.5 miles, turn right and you begin a climb on Stanley Creek Road. The first two miles of Stanley Creek Road are also paved. This gives way to gravel, but the real climbing also begins.
At the top of the climb, turn right into the Rock Creek parking area.