Alpine Dam – Alpine Lake loop from Sleepy Hollow

If you're looking for one of the most challenging and rewarding gravel biking routes in Marin County, the Alpine Dam – Alpine Lake loop from Sleepy Hollow is absolutely worth your time. This difficult 40.9-mile (65.9 km) ride packs in a significant 3311 feet (1009 metres) of elevation gain, typically taking around 4 hours and 41 minutes to complete. It's a true test of endurance and skill, best suited for very fit riders with advanced gravel biking experience.

What to expect on Alpine Dam – Alpine Lake loop from Sleepy Hollow

Expect a journey through diverse and demanding terrain, starting with varied surfaces that include both paved and unpaved sections. The route around Alpine Lake is particularly dynamic, with rolling and weaving paths, tight, twisty sections, and switchbacks that demand your full attention, especially on the climb from the dam. You'll be treated to majestic viewpoints of Mount Tamalpais, the serene Alpine Lake, and dense redwood forests as you traverse the Mt. Tam Watershed. Don't miss the infamous "Seven Sisters," a series of punchy rollers that offer spectacular views, sometimes even glimpses of the Pacific Ocean. Be prepared for challenging climbs and fast descents; some unpaved segments might even require you to push your bike.

Planning your visit

To maximize your enjoyment and safety on this demanding route, it's generally recommended to ride the Alpine Dam – Alpine Lake loop in a counter-clockwise direction. Given the significant elevation gain and technical sections, ensure you have very good fitness and advanced riding skills. While specific parking or permit details aren't highlighted, planning for a full day and checking weather conditions is always wise for such a substantial ride.

Trail details

• Distance: 40.9 miles (65.9 km)
• Elevation gain: 3311 feet (1009 metres)
• Difficulty: difficult
• Estimated time: 4 hours and 41 minutes