Diener 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 Diener Road climb?

3.4 miles (5.5 km) at 4.2% on average, climbing 758 ft (231 m) from 2,031 ft to 2,789 ft. The steepest half kilometre averages 8.7%. That makes it a Category 3 climb.

Where does the climb start and finish?

It starts at 38.90594, -122.67142, and tops out on the road at 38.89082, -122.72049.

Is Diener 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.

• Perini RoadCat 3 · 4.1 mi at 4% · 843 ft · starts 1.7 mi away
• Seigler Canyon RoadCat 3 · 4.6 mi at 3.9% · 942 ft · starts 1.7 mi away
• Prather Mountain RoadCat 3 · 1.1 mi at 9.6% · 548 ft · starts 3.0 mi away
• Observation RoadCat 3 · 1.3 mi at 9.6% · 650 ft · starts 3.7 mi away
• Agua Dulce DriveCat 3 · 1.2 mi at 8.9% · 587 ft · starts 4.0 mi away
• Bottle Rock Road near ClearlakeCat 3 · 3.1 mi at 3.9% · 630 ft · starts 5.9 mi away
• Old Highway 29Cat 3 · 1.3 mi at 10.7% · 735 ft · starts 6.2 mi away
• Saw Mill RoadCat 3 · 2.5 mi at 7.6% · 997 ft · starts 6.5 mi away