Ominous

"The most difficult road bike hill climb in the U.S. and perhaps the world, this road is only open to bikes during the annual hill climb race usually held in August. No concession to gradient was made as it starts out steep and never lets up all the way to the top. Begin at a tollbooth where there is a brief shallow section and then the fun begins. A ramp of 12% grade smacks you in the face to let you know what is in store the rest of the way up the mountain. The grade eases slightly after 0.6 mile but then soon kicks up with rolling ramps of 12-15%. The trees soon begin to thin with some great views although it is difficult to appreciate them as you grind higher.

Approximately 4 miles into the climb you round a bend and for the first time you see what is ahead of you (and it is not a pretty sight): sustained grades of 12-16% along a spectacular ridgeline. After a very steep turn to the left the grade eases as you climb into a tundra. Rolling, slowly increasing grades lead you past the 6,000 ft elevation mark and at mile 7.4 a parking lot appears on the left. Just beyond the lot the steepest part of the climb (22%) greets you, but the end is in sight.

Mt. Washington is about the same length but considerably steeper than the famous Mortirolo in Italy and Angrilu in Spain, generally considered to be the hardest hill climbs used in European cycling tours. Mt. Washington also has generally tougher weather to deal with compared to other top climbs.

If you ever get the chance to ride this hill, congratulate yourself on completing what may be the most difficult road bike climb on Earth."

--John Summerson, The Complete Guide to Climbing