From the parking area, hop across the road to the trailhead where you'll quickly encounter a sturdy wooden bridge with excellent views of the surrounding hills. From here, continue up the trail on steady grades, eventually following the outer extent of a pine grove before reaching a trail junction with the Greyrock Meadows Trail #947
. To remain on this trail (the harder of the two), stay right at the junction and begin a steep climb through forested and open terrain to an upper trail junction.
Once past the upper junction (where #946 and #947 rejoin), there's a short dirt section of trail before climbing a ramp of rock on the southeast side of Greyrock. After leaving the dirt trail, look for the wooden trail posts sporadically placed. There are some easy and solid rocks to scramble as you come up the eastern end. Once into the saddle where folks often camp, look for the rock cairns that will lead you to the top. It's easy to get lost here. If you're scrambling/climbing anything crazy, you're off the direct trail.
Once at the top of the trail, you get a great view of the surrounding area looking down into Fort Collins and up into the canyon. You can also see the Mummy Range in the northern part of RMNP. Generally, the only drawback for most people is the elevation gain; climbing almost 2,000 feet in 3.1 miles is quite the climb in often dry conditions. Planning to do this trail in the morning or a summer evening (bring a headlamp) can be best so you miss the hotter parts of the afternoon.
This isn't the best choice for a first-time runner - there are many places to take wrong turns. However, there are often lots of folks on a summer weekend!
Like anywhere on the Front Range, stay alert for rattlesnakes sunning themselves on the trail.