This is a shortlist, not a ranking. Climbing stats from segment sites depend on where the segment starts and ends, so two sources can disagree; we name the source and segment for each number. Roads change, canyon roads close for fire risk and weather, and traffic varies, so check conditions and ride within your limits.
Modjeska Grade (from Cook's Corner)
The signature short climb at the top of Santiago Canyon. The bikeclimbs.com segment from Cook's Corner to the top of the Modjeska Grade is 1.72 miles with 599 ft of gain at a 6.1% average, with a maximum of 13.4%. It's steep enough to hurt and short enough to repeat, and the descent back toward Cook's Corner is fast, so keep speed in check.
Sources: bikeclimbs.com: Cook's Corner to top of Modjeska Grade
Santiago Canyon Road
The long one. Measured from the Jamboree Rd end to the top of the Modjeska Grade, bikeclimbs.com lists 11.13 miles and 1,081 ft of gain at a 1.8% average, with a maximum of 11.8%. Most of it is a gentle, steady drag through open canyon country, which makes it good for long tempo efforts. Shoulders and traffic vary along the canyon. Route notes: Santiago Canyon to Cook's Corner and our Santiago Canyon & Modjeska climb guide.
Sources: bikeclimbs.com: Santiago, Jamboree to top of Modjeska
Newport Coast Drive
The coastal benchmark. From Pacific Coast Highway up Newport Coast Drive to Vista Ridge, bikeclimbs.com lists 3.57 miles and 939 ft at a 5% average; Irvine Cyclist describes the same climb as about 3.5 miles and 915 ft at roughly 5%, with a few signaled intersections on the way up. For a shorter effort, the segment from Newport Coast Drive to Pelican Hill Rd is 1.54 miles and 473 ft at a 5.8% average. The views back over the ocean are the reward; the descent has turning traffic, so ride it carefully.
Sources: bikeclimbs.com: Newport Coast - Vista Ridge · Irvine Cyclist: Newport Coast climb · bikeclimbs.com: Newport Coast Drive to Pelican Hill Rd
Turtle Rock, Irvine
A favorite short interval climb in Irvine. The Turtle Rock + Starcrest segment on bikeclimbs.com is 1.44 miles and 367 ft at a 4.8% average, with a maximum of 9.9%. Residential streets and a steady grade make it a good place for repeats. See the Turtle Rock ride guide.
Sources: bikeclimbs.com: Turtle Rock + Starcrest
Park Ave, Laguna Beach
The steep one. The bikeclimbs.com segment from Glenneyre to the top is 1.96 miles and 949 ft at a 9.2% average. It's short, but nearly double the average grade of most climbs on this list. Bring low gears, and expect tight streets and parked cars in town.
Sources: bikeclimbs.com: Park Ave, Glenneyre to top
Carbon Canyon Road (SR-142), Brea
North County's climb toward Chino Hills. The bikeclimbs.com segment from the Science Center to the top is 5.50 miles and 685 ft at a 2.4% average, with a maximum of 13.8%. It's a state highway with a winding, narrow section, so ride it when traffic is light. See the Carbon Canyon ride guide.
Sources: bikeclimbs.com: Carbon Canyon Road climb
Ortega Highway (SR-74)
The big mountain road in South County, climbing from San Juan Capistrano into the Santa Ana Mountains toward Lake Elsinore. A published Komoot route to the Ortega Oaks store is about 17.8 miles one way. We don't quote a grade, because the segment sources we checked disagree. It's a busy two-lane highway with limited shoulder in places, best for experienced riders. See the Ortega Highway ride guide.
Sources: Komoot: Ortega Highway to Ortega Oaks · Wikipedia: California State Route 74 (Ortega Highway)
Black Star Canyon (dirt, for gravel bikes)
Not a road climb, but riders keep asking. Black Star Canyon Road is a dirt fire road up the Santa Ana Mountains from Silverado Canyon. MTB Project lists the Blackstar Canyon Road route at 8.6 miles with 2,065 ft of climbing, a 5% average and a 15% maximum. Bring a gravel or mountain bike, plenty of water, and check access and fire closures first.
Sources: MTB Project: Blackstar Canyon Road
Gearing and brakes for OC climbing
If you're grinding on Park Ave or the Modjeska Grade, lower gearing helps more than fitness talk; ask about cassette and chainring options when you service the bike. Long canyon descents heat brakes, so make sure pads have life left and hydraulic brakes are bled; see our guide to hydraulic disc brakes on OC climbs. A professional bike fit also makes long climbs easier on your back and knees.
More rides and the right bike
All our route write-ups, flat and hilly, are on the rides page, and best road rides in Orange County covers the classic loops. Shopping for a climbing bike? See our road bike shop in Orange County page for Pinarello, Colnago, Bianchi and Cervélo, or call (714) 760-4908.
Quick answers
What is the hardest road climb in Orange County?
It depends on how you measure it. Of the climbs in this guide, Park Ave in Laguna Beach has the steepest average (9.2% over 1.96 miles on bikeclimbs.com), while Ortega Highway and Santiago Canyon are the longest.
How long is the Modjeska Grade?
The bikeclimbs.com segment from Cook's Corner to the top of the Modjeska Grade is 1.72 miles with 599 ft of gain at a 6.1% average.
How long is the Newport Coast climb?
From PCH to Vista Ridge, bikeclimbs.com lists 3.57 miles and 939 ft at a 5% average; Irvine Cyclist describes it as about 3.5 miles and 915 ft.
Road and trail conditions change. Check closures before you ride, and ride within your limits.