Top Bike Climbs in America

In his book The Complete Guide to Climbing (by Bike) 2nd ed., John Summerson gives a great overview of the 100 hardest climbs in America, many of which are located in California and Colorado.
He developed his own rating method, which is similar to the rating method used at TourOfCalifornia.org with additional adjustments for altitude, average grade, grade variability, and road surface.
Eastern Sierra
Eastern Sierra
Below is an overview of the top ten climbs (* indicates not in the book). The book covers additional categories as well as many more climbs with relevant details.

Most Difficult Climbs

1. Mount Washington, NH (Multi-Surface)
2. Pikes Peak, CO
3. Mauna Loa, HI
4. Haleakala, HI
5. The Bear, CA
6. Mauna Kea, HI
9. Kaloko Drive, HI
10. Guardsman Pass, UT

Greatest Elevation Gained

1. Mauna Loa, HI - 11,091 feet
2. Haleakala, HI - 9,997 feet
3. Mauna Kea, HI - 9,117 feet
4. Pikes Peak, CO - 7,882 feet
5. Mount Baldy Notch, CA (Multi-Surface) - 6,784 feet *
6. Mount Evans, CO - 6,590 feet
7. Dawson Saddle, CA - 6,428 feet
8. Horseshoe Meadows, CA - 6,234 feet
9. Mount Lemmon, AZ - 6,222 feet
10. 190, CA - 6,199 feet

Highest Elevation Attained

1. White Mountain Peak, CA (Multi-Surface) - 14,252 feet *
2. Mount Evans, CO - 14,127 feet
3. Pikes Peak, CO - 14,110 feet
4. Trail Ridge Road, CO (Highest Pass) - 12,183 feet
5. Cottonwood Pass, CO - 12,126 feet
6. Independence Pass, CO - 12,095 feet
7. Loveland Pass, CO - 11,992 feet
8. Guanella Pass, CO - 11,700 feet
9. Hoosier Pass, CO - 11,541 feet
10. Slumgullion Pass, CO - 11,530 feet

Most Scenic/Spectacular Climbs

2. Red Mountain Pass, CO
4. Beartooth Pass, MT
5. Alpine Summit, UT
7. McKenzie Pass, OR
8. Cherohala Skyway, NC
9. Mount Baker, WA
10. Castle Valley, UT
By:
See Also: Top Bike Climbs in California