The steepest 2 kilometers of the top cycling climbs in the United States. From this page you may navigate to the top 10 steepest bicycling climbs in the USA. The US steepest bike climbs we have documented are featured in the slideshow below. Scroll down to access the US steepest 2 km Top 10 Bicycle Climbs "Table". The cycling climbs covering the steepest 2 kilometer gradients in the US, and some of the world's hardest and most scenic cycling climbs are, in order of steepness, 1. Burke Mountain, 2. Panther Mountain, 3. Socrates Mine Road, 4. Kaloko Dr, 5. Mt. Ascutney, 6. Mix Canyon, 7. Mountain Road - Brookings, 8. Lincoln Gap East, 9. Old Priest Grade, and 10. Iowa Hill Road West.