The best link-up of the technical descending in the Brainard Lake area. When ridden as described, the climbs are tough but mostly manageable for strong riders and the descents are fully engaging.
The sections near Brainard Lake skirt the wilderness boundary and care should be taken to not venture onto trails that are closed to bicycles.
Unless you're very experienced in this type of technical riding, expect to dismount frequently during the course of the ride.The rock gardens on the downhill sections of the latter half of the ride are especially challenging.
From the South Saint Vrain Trailhead near the Peak to Peak (Highway 72), climb up Road 96 to the junction with the North Sourdough. Take North Sourdough to the south (left). Cross over the South Saint Vrain Trail and continue to Brainard Lake Road. Cross Brainard Lake Road to Road 2321 (passing the junction with Sourdough Trail - Southern Half on your left.
Ride up Road 2321 until the Little Raven Trail
. Head north on Little Raven Trail
until you get back to Brainard Lake Road. Head right on Brainard Lake Road for a short distance then turn left on the unmarked trail that crosses the meadow. Go left on the Brainard Lake Road for a few hundred feet to the kiosk on the right and the start of the South Saint Vrain Spur. Take the South Saint Vrain Spur to the main South Saint Vrain Trail being careful to turn right (left is off limits to bicycles). Ride the South Saint Vrain Trail all the way back to your start.