Northwest of Denver near Allenspark, the Buchanan Pass Trail (aka Middle St. Vrain Trail) is open to horseback riding.
From the Middle Saint Vrain Trailhead, the Buchanan Pass Trail #910 parallels the north side of the Middle Saint Vrain Creek. It is a gradual climb, from 8,600 feet to 9,800 feet in 3.8 miles, to the Middle Saint Vrain 4x4 Trailhead. The first half mile of trail is day-use only. The next three miles are open to dispersed camping and no permits are required. Check with the Boulder Ranger District office regarding possible campfire restrictions. At the Middle Saint Vrain 4x4 Trailhead, the Buchanan Pass Trail picks up the old road which follows the creek on a gentle uphill grade. In a short distance, it comes into a large meadow with fine views of Elktooth. The Indian Peaks Wilderness boundary is 0.6 miles to the west of the Middle Saint Vrain 4x4 Trailhead. Backcountry permits are required for camping within the Indian Peaks Wilderness. At the wilderness boundary the Buchanan Pass Trail intersects the Saint Vrain Mountain Trail #915, which heads uphill to the northeast. The Buchanan Pass Trail continues up-valley for 0.9 miles before intersecting the Saint Vrain Glacier Trail #917. Right after the intersection, the Buchanan Pass Trail crosses the creek on a narrow bridge and hooks to the south, heading down-valley on an old pack trail, that ascends the slope for 1.1 miles to the 0.6 mile spur trail to Red Deer Lake (elevation 10,372). Another 0.8 miles past the Red Deer spur trail, after crossing into the next valley, the Buchanan Pass trail meets the Beaver Creek Trail #911 1.6 miles west of the Coney Flats Trailhead. From there, the Buchanan Pass Trail climbs more steeply west to Buchanan Pass (elevation 11,837 ) at the Continental Divide. The northeast-facing pass holds snow late into the summer, which can become very hard and icy. In very late snow years, the pass retains snow all summer. Continuing westward on the Buchanan Pass Trail, you would reach the Monarch Lake Trailhead, after hiking an additional 10 miles. The Buchanan Pass Trail takes you through spruce/fir woodlands and riparian meadows, and offers spectacular views of rugged peaks and majestic alpine lakes and meadows. Note: The Red Deer Lake Cut-Off Trail, shown on the Allenspark quad, no longer exists.
Directions: From Lyons, go west on SR 7 for 15 miles. Turn left (south) on SR 72 and go 4.1 miles. Turn right at Peaceful Valley area onto the road to Camp Dick. Go 1 mile to parking.
Overall, Buchanan/Middle St. Vrain Trail is the 49th most popular horse trail of all 66 horseback rides in Colorado.