Steepest Gradient (%)
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Cycling Socrates Mine Road, Lake County, California
Ride 3.5 miles gaining 1,818’ at 9.9% average grade.
This is the third highest FIETs Index ranked climb in the Sonoma-Napa-Lake Counties area, and the highest fully paved (Mt. St Helena is no.1 and Bald Mt no. 2, but cross bikes are recommended for them).
Climb begins off Highway 175 just north of Middletown.
Another interesting feature on Socrates Mine Road is its three runaway truck ramps available for the unfortunate trucker, something we have not seen on any other rural narrow remote non-highway we have ridden. This ride is epic and highly recommended for serious climbers. Check out our YouTube video of the climb here.
Three -- count em -- three runaway truck ramps.
Sights along the way . . . other than the pavement in front of you while you struggle up terribly steep grades. 😓
Stay on road.
This brute is located in the Mayacamas Mountain Range, a subrange of the Pacific Coast Range. The road gets its name from the long abandoned Socrates Mercury Mine which operated during the Northbay’s quicksilver boom in the late 1800s. The mine was reopened for a time in the 1960s due to a dramatic increase in the price of quicksilver which made the mine once again valuable, albeit for a brief period of time.
Photo from Healdsburg Tribune’s July 1, 1965 issue.
URC Center for Bibliographical Studies and Research, California Digital Newspaper Collection.
Surveyor’s map of Socrates Mine (circa 1903)
The Socrates Tunnel was about 200’ below the surface.
(The Quicksilver Resources of California, p. 116)
The extreme challenge of this climb begins at mile 2.2 and continues unabated to the top, averaging a startling 15.3% for the final 1.3 miles -- all the more challenging during the summer when temperatures often approach and exceed 100 degrees.
Climb ends at Calpine power station Big Geysers Unit 13.
Finish at a geothermal power plant
Roadway Surface and Traffic Report: The roadway is mildly deteriorated, but manageable. This is a two-lane remote road that has no bike lane, but has very low traffic flow.
That’s a wrap!!