The steepest 2 kilometers of the top cycling climbs in California. From this page you may navigate to the top 10 steepest bicycling climbs in CA. California's steepest bike climbs we have documented are featured in the slideshow below. Scroll down to access California's steepest 2 km Top 10 Bicycle Climbs "Table". The cycling climbs covering the steepest 2 kilometer gradients in CA, and some of California's hardest and most scenic cycling climbs are, in order of steepness, 1. Socrates Mine Road, 2. Mix Canyon, 3. Old Priest Grade, 4. Iowa Hill Road West, 5. Welch Creek Road, 6. Tuna Canyon from PCH, 7. Bohlman - On Orbit, 8. Rancheria Wall, 9. Las Flores to Stunt Road, and 10. Bullfrog Pond.