Sly Park Road Climb

We don't rate roads as safe or unsafe: crash counts can't say how risky a ride is, and roads people like to ride draw more riders, so they see more crashes. What the records show: no bike crashes were reported along the climb from 2021–2025.

How long and steep is the Sly Park Road climb?

12 miles (19.9 km) at 3.7% on average, climbing 2,441 ft (744 m) from 1,811 ft to 4,252 ft. The steepest half kilometre averages 9.3%. That makes it a Category 1 climb.

Where does the climb start and finish?

It starts at 38.65867, -120.67815, where Sly Park Road leaves Mount Aukum Road, and tops out on the road at 38.75567, -120.5572.

Is Sly Park Road paved?

Yes, by its OpenStreetMap tags.

How is the category worked out?

From the climb's shape only: length in metres × average grade (%) of 16,000 or more for Cat 3, 32,000 for Cat 2, 64,000 for Cat 1 and 80,000 for HC. It describes how hard the climb is, not traffic or crashes.

Where does this data come from?

The climb is found from OpenStreetMap roads and USGS 3DEP elevation (every climb, not a list of famous ones). Access is from OpenStreetMap tags; gates and closures change, so obey posted signs. Crash counts are police reports in the California Crash Reporting System (CCRS) on data.ca.gov, counted where their map location is within 100 ft of the climb. The forecast is from the National Weather Service.

• Grizzly Flat Road from Mount Aukum RoadCat 2 · 5.7 mi at 3.5% · 1,076 ft · starts 0.9 mi away
• Bucks Bar RoadCat 3 · 2.6 mi at 5.7% · 781 ft · starts 1.3 mi away
• Happy Valley Road near PlacervilleCat 1 · 6.4 mi at 7% · 2,343 ft · starts 2.6 mi away
• Starkes Grade RoadCat 2 · 6.7 mi at 4.2% · 1,490 ft · starts 2.7 mi away
• Clear Creek Road from Rivendale RoadCat 3 · 2.7 mi at 4.2% · 600 ft · starts 2.8 mi away
• Sweeney DriveCat 3 · 3.3 mi at 5.8% · 1,007 ft · starts 2.9 mi away
• Red Robin RoadCat 3 · 1.8 mi at 8% · 771 ft · starts 3.5 mi away
• Ladies Valley RoadCat 3 · 1.6 mi at 9.5% · 823 ft · starts 3.6 mi away