Advice and Description of the ride up Mt. Diablo
-Joe Shami, Dec 2011
When riding Mt. Diablo in winter months, I strongly recommend bringing a knapsack with warm clothing, such as winter gloves, head warmer, a dry, long-sleeve undershirt if you intend to go to the summit, a light wind-breaker jacket, long pants (of course), and even a balaclava if you have one and silk glove liners. You may resent the extra weight while climbing, especially on that last 0.14 mile of 17% slope up to the Summit, but you may thank me on the descent, because your clothing will be wet from sweat by the time you reach the top, and you’ll be sitting motionless on the descent for a half hour, so one can get unpleasantly freezing.
Mt. Diablo is a difficult climb with three different weather zones, and the wind can be a big factor. There is an automated weather line (925-838-9225) that is updated every 20 minutes that gives the temperature and average wind condition at the summit, but it has been out of action for a couple of weeks with a busy signal and is right now.
Except for that 17% climb at the end, most of the rest of the climb is rarely more than 10%, but if you don’t have extra-low gears, you’ll certainly notice those long stretches of 8%, 9%, and 10%.
The altitude at the summit is 3849 ft; at the Junction, a possible turn-around point, it’s 2200 ft. When climbing Southgate, you’re protected by a ridge for the first 2.5 miles till you reach the Toll Gate at about 1500 ft. Then, it can become windier. The next Weather Zone is just above the parking lot at Juniper Campground at 3,000 ft. It’s not always worse above that. Sometimes, you’re above the fog at this time of year, and it’s warm and pleasant there, till you come back down into the sea of fog, which may not have burned off yet.
Once you enter the State Park on Mt. Diablo Scenic Blvd — the road you take from Athenian School — it’s about 5.75 miles to the Junction with Northgate Rd. Then it’s 4.5 tougher miles to the Summit. There are mileage marks every quarter mile by the side of the road. In addition, when climbing Southgate, you’ll see an initial marker with the number 59 (I think). Then you’ll see countdown numbers after that, counting down to zero, which is the Junction.
Watch out for absolutely terrible potholes in the one-mile stretch from Athenian School to the State Park entrance. Within the park, Southgate Rd is in good condition, as is Summit Rd. However, Northgate Rd (which you won’t be accessing tomorrow) is NOT in good condition and is harder and steeper and longer (6.5 miles once you enter the State Park from Walnut Creek).
When descending the mountain alone, I try to have a flashing headlight, because the greatest danger on a busy weekend is from stupid drivers who think they have the road to themselves and pass uphill cyclists on blind curves.