Cycling Pine Flat Road - Sonoma County’s 4th difficult bike climb
Ride 11.2 miles to 3,158’ gaining 3,589’ at 4.9% average grade.
This climb ranks #7 on the Tri-County Top 25 list with a Fiets Index of 4.44. The first 7 miles of Pine Flat (to “the guardrail” as the locals refer to it) are a modest ascent at 5.5% average grade which is followed by 2.1 miles that actually averages -0.8% grade (perhaps where the "flat" part of the road's name comes from). The biggest challenge of this climb comes towards the end, with the last 2.2 miles averaging 9.2% and 1.1 mile at the beginning of that stretch averaging 11.4% (20% for a brief time on "The Wall" at the 10.1 mile mark.) The upper portion of the ride approaches The Geysers area and can be torturously hot in the summer.
Pine Flat is located in the Mayacamas Mountains which stretch 52 miles from Clear Lake to northern Sonoma and Napa counties.
Looking back from the start via drone aerial photo.
First stretch of Pine Flat Road
Lower portion of the climb.
Cyclist on The Wall
The Wall - ¼ mile at 16% beginning at mile 10.2
Read it and weep - the Garmin don’t lie!
Peak gradient on The Wall
Section just after The Wall.
Rounding the bend on the way to the finish.
The first 5 1/2 miles (to the pond) offer magnificent vineyard views along Pine Flat Road, while the next 1 1/2 miles give us views of the Alexander Valley to the west, Mt. St. Helena to the southeast (photo) and, if we look carefully and know what we are looking for, Mt. Tamalpais to the south (photo).
Supplies: The Jimtown store is less than a mile from the start of the ride.
Roadway surface/Traffic: The roadway is in decent condition at the bottom, with moderate deterioration towards the top. Caution is required for the decent as the upper portion of the mountain is very steep with rough road, sharp turns and gravel in many locations. Traffic over the entire climb is minimal.