Mount Diablo climbs 10.5 miles (16.9 km) at an average of 5.7% from Mt. Diablo Scenic Boulevard in the town of Diablo (659 ft / 201 m) to the summit (3,822 ft / 1,165 m), with 3,189 ft (972 m) of climbing. It’s the best-known climb in the San Francisco Bay Area and one that every local rider has on their list, along with Mount Tamalpais and Mount Hamilton.
What the climb is like
- South Gate to Junction (mile 0-6.1). You start about a third of a mile (500 m) before the state park entrance. The road climbs at a steady grade, mostly between 5% and 8%. At the Junction ranger station there’s a water fountain behind the building. This is also where North Gate Road comes in.
- Summit Road (mile 6.1-10.5). Turn right. About 2 miles (3 km) from the top is the hardest sustained stretch (1 mile / 1.6 km at 8.4%) and, at the very end, the wall: the last 984 ft (300 m) are around 15% and the final 328 ft (100 m) hit 16%.
At the top there’s a museum with an observation deck and a drinks vending machine. The 360-degree views take in much of the Bay Area.
PJAMM measures 10.5 miles (16.9 km) and 3,189 ft (972 m); Climbfinder starts a bit lower and gives 10.9 miles (17.6 km) and 3,294 ft (1,004 m), with the summit at 3,835 ft (1,169 m). Both agree on a steepest pitch of 16%.
History
The Tour of California finished on the summit several times, with stage wins by riders including Leopold König and Rohan Dennis. Mount Diablo is a state park and a classic Bay Area viewpoint.
When to go and traffic
You can ride it year-round. In summer the lower slopes get very hot: start early. In winter the summit can be foggy and cold. Traffic moves slowly (the speed limit in the park is 25 mph / 40 km/h) and there are “share the road” signs the whole way. PJAMM notes that cyclists didn’t pay an entry fee as of 2021; cars do pay in some areas of the park. Park on the street in the first half mile or near the Athenian School.
It’s easy to combine with a trip to San Francisco: the base is about 31 miles (50 km) from the city. Altitude isn’t a factor.
What gearing to use
A 34x28 is enough for almost the whole climb. For the 16% wall at the finish, if you’re running low on strength, you’ll be glad of a 34x32. Check your combinations in the gear calculator.
Frequently asked questions
How long does it take to bike up Mount Diablo?
A 159 lb (72 kg) rider on a 21 lb (9.5 kg) bike takes about 1 h 10 min at 3 W/kg (216 W), 1 h 22 min at 2.5 W/kg and 55 min at 4 W/kg. Work out your own time with your weight and power in the calculator on this page.
What is the hardest part of Mount Diablo?
The finish: the last 984 ft (300 m) average around 15% and the final 328 ft (100 m) before the summit hit 16%. Until then the grade is steady, mostly between 5% and 10%.
Can you climb Mount Diablo from the north?
Yes. North Gate Road, from Walnut Creek, joins the South Gate road at the Junction ranger station, and from there they share the last 4.3 miles (7 km) to the summit.