Distance: 36 miles out and back
Elevation gain: 4750 ft
(A Best of the Best ride)
This is a grande dame of a ride, one of the three iconic climbs in the Bay Area—Hamilton, Mt. Tam, and Diablo. It’s quite long—18.2 miles one way, all but a mile or so significantly up. It’s much more sustained climbing than either of the other two icons, and it’s considerably over our 100 ft/mile benchmark for climbing difficulty. Still, it’s easier than the numbers make it look. When they built the Lick Observatory at the summit, starting in 1876, they needed to haul massive equipment up the road by mule, so they had to make the road at a shallow enough pitch that the mules could handle it. So it’s a constant 5-7%—not a moment of 8% in the whole 36 miles. And there are two nice descents along the way up to rest your legs. Nevertheless, it’s work, just because there’s so much of it. You’ll be climbing, with two brief breaks, for something like 3 hours.
The route is all through pretty East Bay oak-strewn hills, and the road contour is constantly rewarding (endless serpentining) after the first couple of miles. The vistas of San Jose, the southern end of SF Bay, and lands to the south start out grand and get more incredible as you ascend. The descent used to be hampered by poor pavement, but the road from the observatory to Grant Park has just (in 2021) been repaved and now it’s all flawless and world-class. And the observatory at the top is simply fascinating. All in all, a bucket-list ride, marred only by the fact that 16 miles of essentially unaltered 6% climbing gets a little monotonous.
(To see an interactive version of the map/elevation profile, click on the ride name, upper left, wait for the new map to load, then click on the “full screen” icon, upper right.)
Start at the beginning of Mt. Hamilton Rd., where it takes off from Alum Rock Rd. The Berryessa BART station will get you within about 4.5 miles of the start (so 9 miles round-trip) and will add c. 400 ft to the elevation gain. If you drive, there are dirt pull-outs for parking on both sides of Alum Rock Rd. at the intersection, and there is plenty of curbside parking available in front of houses in the nearby neighborhoods. There is no flat road anywhere nearby to warm up on, but the pitch of Mt. Hamilton Rd itself is mild enough that you can warm up on the climb. The first couple of miles ascend rather monotonously up a sidehill, but soon the pitch lessens and the road begins to serpentine deliciously, and it will continue to do so to the end of the ride. When the road surface turns poor, you cross a ridge and get a 2-mile descent to Joseph D. Grant County Park, in a pleasant green valley (during the rainy season) between the hills with trails, campgrounds, bathrooms, and water (there’s a spigot right across from the money collection kiosk at the entrance). It’s a nice place to kick back and eat your PB and J. They’re supposed to charge you $6, but they might let a bicycle pass. The water is free in any case.
After Grant the road surface goes back to flawless and the serpentining gets even better. The road will get steadily windier as you ascend until in the last miles before the observatory it’s practically comical. There is a spot very near the turn-around where you can see below you ten distinct segments of Mr. Hamilton Rd. at once (counting the one you’re standing on).
After a second little descent drops down to a bridge, the rest of the ride is more of the same, now with frequent glimpses of your destination, the Observatory, on the summit ahead of you.
The Observatory itself is fascinating, so definitely plan at least a couple of hours there. There are exhibits on the old telescope and how it was built and transported up the mountain, the telescope itself (straight out of Jules Verne), a charming inner courtyard where I love to sit and breathe the negative ions from the water fountain, and a gift shop.
The Observatory is very bike-friendly. Continue on through the parking lot around to the right and you’ll find a bike rack, a sign reading “Please remove or cover cleats,” and a door to good bathrooms, a Coke machine, and a drinking fountain. The fountain even has a water-bottle-friendly spout. Go straight through the second door to get to the courtyard.
The Observatory is often closed to the public, so check visiting hours if you’re interested, but the restrooms, drinking fountain, and Coke machine are open 8-5 daily.
The ride back varies from good to great. The first couple of miles are too twisty to be unqualifiedly joyful. You’re on your brakes most of the time, often hard on them, you’ll do a lot of 9-mph corners, and you can’t sustain any rhythm. Then the road straightens out just a little, and that makes all the difference—it’s excellent for the three miles to the bridge. After the short climb, the descent to Grant Park is my favorite descending section on the route—the curves are large enough and sweeping enough that you can sustain a lot of speed, and gentle touches on the brakes will suffice.
Much of the descending is high drama thanks to two factors: 1) on your L you have what seems like the entire world open before you, enormous open spaces and precipitous drop-offs, and 2) Santa Clara County has apparently decided it has better things to do with its money than install guard rails, because there are none. One missed right-hander and you’re dead. Mount Diablo and Mt. Tam have no drop-offs worth mentioning and thus can’t compare in sheer fear factor.
Which of the three iconic rides has the best descending? I can’t say—they’re each outstanding in their own way.
After the moderately long climb out of Grant, the serpentining continues for a mile or so, and it’s actually some of the best descending on the route, because you’re crossing the top of the ridge so the pitch is gentler and you can attack it harder. The last miles are tamer, straighter, but still good, and on any other ride they would be praise-worthy, but by then the descending bar has been raised so high they feel routine.
By the way, both climbs on the return are more than mere bumps, but they’re mellow and nothing to fear, even with tired legs.
Shortening the route: Start at Grant Park.
Adding miles: The Sierra Road ride is a stone’s throw to your north. A short car trip to the south is Metcalf Rd., made famous in the 2013 Tour of California as the last 3K of the time trial. It’s a lot like Sierra, a seriously steep climb people ride for the glory of it.
A lot of people who ride Mt. Hamilton do it as part of a long semi-loop: ride BART to Berryessa, ride to Mt. Hamilton Rd. and up to the Observatory, then just keep on going, down the back side of the mountain to Mines Rd. and the Dublin BART station. This route is frequently ridden in the opposite direction. Either route takes you right past the turn-around spot of our Del Puerto Canyon Road ride. This is the dry side of the mountain, so the landscape is stark.
Afterthoughts: East of San Jose in summer is HOT, and, while you are riding past oaks, they don’t canopy the road, so it’s an exposed ride. Try to avoid summer afternoons, carry a lot of water and food, and refill your water bottles at Grant and the observatory.