Bolinas and San Geronimo Ridge Loop

The estimated duration for this mountain bike loop is around 3 hours and 40 minutes. However, given its challenging nature with significant climbs and descents, actual completion time can vary widely based on your fitness level, riding speed, and how often you stop to enjoy the views or navigate difficult sections.

No, this loop is generally considered difficult and is not recommended for beginners. It requires very good fitness and advanced riding skills due to significant elevation changes, steep climbs (some requiring hike-a-bike), rocky sections, and relentless 'rollers' on San Geronimo Ridge.

The terrain is highly diverse, featuring a mix of fire roads, paved sections, and some rocky descents. You'll encounter constantly trending downhill sections on Bolinas Ridge, which can be rocky and uneven. San Geronimo Ridge is characterized by numerous steep ups and downs, often described as 'rollers'. Sections like Shafter Grade are notably steep, averaging 13% over 1.5 miles, where you might need to hike your bike. The Cross Marin Trail offers smoother, flatter paved and gravel sections through redwood forests.

The loop offers spectacular and varied scenery. You'll enjoy great views of Tomales Bay from Bolinas Ridge, and from San Geronimo Ridge, you can see the Pacific Ocean to the west and the San Francisco Bay to the east. The route also passes through beautiful redwood groves and semi-open meadowland, particularly along the Lagunitas Creek on the Cross Marin Trail section.

Yes, as this trail is located within the Mount Tamalpais Watershed, there are specific regulations. While there are generally no entrance fees for day use, certain activities or areas might require permits. It's always best to check the official Marin Municipal Water District (MMWD) website for the most current rules and any specific permit requirements before your ride.

Specific parking details can vary depending on your chosen starting point for the loop. Common access points might include areas near Bolinas or San Geronimo. We recommend checking detailed maps or local resources for designated parking areas closest to your planned trailhead. Always be mindful of local parking regulations and private property.

Regulations regarding dogs can vary within the Mount Tamalpais Watershed. Generally, dogs are permitted on leash on many fire roads and trails, but there might be restrictions in certain sensitive areas or on specific trails. It's crucial to consult the Marin Municipal Water District (MMWD) website for their most current and specific dog policies to ensure compliance.

The best time to ride this loop is typically during the drier months, from late spring through early fall. This avoids the muddy and potentially hazardous conditions that can occur during the rainy winter season. Clear weather also enhances the spectacular views. Always check the local weather forecast before heading out.

Yes, the route incorporates sections of several other trails. You'll find yourself on parts of the Bay Area Ridge Trail - 01 - North Bay, ADT - California - T - Seg 9, Sir Francis Drake Bike Route, Cross Marin Trail, and significant portions of the Bolinas Ridge Trail, Kent Pump Fire Road, and San Geronimo Ridge Road, among others.

Absolutely. The climb up Shafter Grade is frequently highlighted as a 'soul-crusher' due to its steepness, often requiring riders to hike-a-bike. The 'rollers' on San Geronimo Ridge also present a continuous challenge with their steep ups and downs. Additionally, some parts of Bolinas Ridge can be quite rocky and uneven, demanding good bike handling skills.

Given the loop's difficulty and length, it's essential to be well-prepared. Bring plenty of water, snacks, a repair kit for your bike (including tubes and tools), a first-aid kit, sun protection, and appropriate layers of clothing. A reliable GPS device or map is also highly recommended due to the interconnected nature of the trails.