Supplied by the Boulder County Cartographer

Lefthand to top ~6.3%
Lefthand: 36 to Ward/Jamestown cutoff ~2.8%
James Canyon Dr to Jamestown ~4.2%
Lefthand to Ward ~4.7%

Hwy 7/St. Vrain: ~4.1%Flagstaff: ~6.6%

Sugarloaf: ~8.4%

Magnolia: ~9.3%

Four Mile Canyon: ~3.5%
Sunshine ~6.7%
Old Stage: Lee Hill side to top ~5.6%

Lee Hill: West out of town ~6.8%
East towards town ~6.8%

The information below is from The Guide to Bicycling the Roads out of Boulder by Burt and Terry Struthers.

Flagstaff Rd – from Gregory Canyon at end of Baseline. The first 5 miles have an average grade of 7.4% with a .3 mile section just below Lost Gulch Overlook at 14%. The first .5 mile above Gregory Canyon averages 10%, the 3.5 miles from Gregory Canyon to the Ampitheater turnoff averages 6.5, and the next two miles to the exit from the Mountain Park averages 10%.

Sunshine Canyon – from end of Mapleton. The first 4.5 miles have an average grade of 6.7% with short stretchos up to 14%.

Lee Hill/Olde Stage Rds – west on Lee Hill from Broadway. The climb up Olde Stage features about an 8% average grade. The first mile of Lee Hill beyond the Olde Stage turn-off is 11%.

Lefthand Canyon – from Greenbriar Restaurant to Ward. The first 16.5 miles average 4% grade, but the last 1.5 mile climb to Ward is 10%.

Jamestown – from Greenbriar Restaurant to Jamestown turnoff to above Jamestown. The three-mile section from the Jamestown turnoff to town averages 4.5% grade, with a 2.5 mile stretch above town at 8.3%

Lick Skillet Rd – from Lick Skillet in Left Hand Canyon to Gold Hill. This is a gravel road, climbs 800 feet in one mile for a 15% grade.

Magnolia Rd – from Boulder Canyon. The first 4 miles have an average grade of 9% with a section at the bottom over 13%. Drawback to this ride is a busy approach through Boulder Canyon.

Sugarloaf Rd – from Boulder Canyon. The first 4 miles average between 6% and 7% grades. Drawback to this ride is a busy approach through Boulder Canyon.

Peak to Peak Hwy – north from Nederland to Allenspark. Four miles north of Nederland sustains an average grade of 7.7% for two miles. The return trip from Allenspark has 7.5% for one mile (three miles south of Colo. 7)

Golden Gate Canyon – west on Golden Gate Canyon Rd from Colo. 93. The road climbs for nearly 13 miles with an average grade of 6.5% and a one-mile stretch near the top at over 10%.

NCAR Rd – from NIST up bike path up Hollyberry Rd to Deer Valley Rd to Table Mesa. Average grade is 5.7% with sections up to 8% grade.

Modified Morgul-Bismarck – from Marshall Road (Colo. 170) to south on McCaslin Blvd to west on Airport Rd (Colo. 128). On McCaslin, The Hump is 8% grade, The Wall is 12%, and a section on Colo. 128 is 6.5% – each shorter than a mile. Due to high traffic on Colo. 93, don’t complete the loop but retrace your route the way you came.

Carter Lake – north from Boulder. After approximately 30 miles of flat, the climb to Carter Lake averages a grade of 6.4%