Flagstaff Road is the climb in Boulder.
Length: 4.55 miles (7.32km)
Average Grade: 8.5%
Maximum Grade: 12.8%
Vertical Gain: 2060 ft (628m)
Summit: 7700 ft (2347m)
Tour de France Category: 1
Tour de France analogue:
Ax 3 Domaines – Final climb, Stage 14, 2010 TdF
There is usually light traffic on this road. It is mostly used by locals who live in the mountains (traffic down in the morning, up in the evening), and by tourists. However, the road is narrow with no shoulder.
Baseline Road, named for its exact 40 degrees north latitude, heads west from Broadway past Chautauqua Park and the famous view of the Flatirons. The climb is usually measured from the right turn across the stone bridge where Baseline becomes Flagstaff Road.
The climb starts abruptly and the first mile up to the overlook is very steep with the first mile averaging 8.6% grade. After the Flagstaff House Restaurant the grade eases somewhat for a second mile at 5.5%. There are two more tight switchbacks and then a flatter section leading to the final push to the amphitheater turnoff. The third mile to the turnoff is 6.1%.
Most people turn right and follow the gentler climb for about 1/2 mile to the amphitheater overlook. Those in the know understand the climb has barely even started. The 1.5 miles beyond ascend as many vertical feet as the 3 miles to the turnoff.
The fourth mile averages 10.8% grade, and 12.8% for 3/4 mile. There is a brief respite as you pass the Panorama Overlook, but you quickly reach the final, steep switchbacks with the final 0.5 mile averaging a cool 9.9% grade.
Some choose to descend the backside until the road turns to dirt (“Where the sidewalk ends”) and turn around there. Either way, enjoy your descent!