South St. Vrain Trail (East)
This trail is a classic for some of the more gnarly technical moves you'll find in Boulder County. There are boulders and more boulders, switchbacky steps that come out of nowhere, and trees too close to the trail which will catch or mangle you when you fly off the bars. That said, the techy spots are interspersed with plenty of trail to make the faint of heart happy too - sweet singletrack, open-er-up rocky sections which a 5" bike can handle, and some really beautiful forest. Take one of the gnarliest sections of single track in the Front Range, combine it with fast double track, sinuous single track through aspens and spring flowers, multiple steep and loose sections to keep you on your toes, then add a healthy serving of basketball sized embedded rock... and you've got the South St Vrain trail.
SSV is a gem and you gotta ride it at least once... but for at least your first time, definitely do it downhill by starting at the Brainard Lake end and riding down to Beaver Res Road. Once you get to the road, take a left and climb up to the Sourdough Trail; you'll find the trail crossing the road about 200 yards from the reservoir. Take a left onto Sourdough to return to Brainard.
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