Bills
A steady but challenging gravel climb up smooth single track to steep fire roads. Suitable for mountain or gravel bikes.
About This Route
Bills is the entry point to Marin's world-class off-road riding. This 28-mile route combines smooth singletrack, fire roads, and some pavement to create a ride that showcases the best of what the Mount Tamalpais watershed has to offer.
The route starts with a gradual climb on well-maintained fire roads, easing you into the terrain. As you gain elevation, the singletrack sections begin - flowing, smooth trails that wind through stands of bay laurel and live oak. These are some of the best-maintained trails in Marin, and the riding is pure joy.
The middle portion of the route hits the steep stuff. Fire road climbs with grades that push 15-20% test your low-gear spinning ability and your willingness to suffer. But the payoff is huge: ridgeline views that stretch from the Pacific to the Bay, and descents that reward confident bike handling.
This route works on either a mountain bike or a gravel bike, though the steeper fire road sections and loose surface favor wider tires. If you're new to off-road riding in Marin, this is the perfect introduction - challenging enough to be interesting, but not so technical that you need advanced mountain biking skills.
Tips
- 40mm+ tires recommended for the fire road sections - narrower tires will struggle on loose gravel
- The steep fire road climbs are rideable but barely - don't be ashamed to walk a short section
- Bring more water than you think you need - the climbing generates serious thirst
- The singletrack sections are shared with hikers - yield and be courteous
- Start from the Fairfax side for the most gradual warm-up to the climbing