This route has one good climb for everyone, two good climbs for humanes on up, and three good climbs for the intermediate and advanced...But that's not why they call it The Three Bears.
The route starts with Tunnel-Grizzly, the first good climb.
Tunnel-GrizzlyTunnel-Grizzly might the best known local climb. Grizzly Peak is the tallest hill and most visible point from the many places on the west side of the bay.
For Light riders—If you've been riding and doing at least some climbing—if you're getting into cycling shape, this will be a good climb.
My favorite part is that on a clear day, Grizzly Peak has the most gorgeous panoramic views of the city and Golden Gate that you could want... You can see the Farallone Islands on clear mornings.
Grizzly is a double hump. After a bit of a climb, you drop down steeply to a four-way stop at the Claremont/Fish Ranch Road intersection. There can be crossing car traffic to watch for... and then you climb the second, taller hump.
On that last climb, the road is narrow, no bike lane, rutted and pot-holed in places.. Watch out for the gravel and rocks along the right side.
If you stop at the Steam Trains for water or the rest rooms before the descent ... the trains don't start until 11 a.m., so you probably won't see them... if you haven't seen them, go back sometime when you can. They are great and a total delight to young kids (of all ages).
When you leave the steam trains, watch for pot holes for the mile or so to Golf Course Rd.—where you then do a sweeping descent to Wildcat Canyon and then to Inspiration Point with its signature awe-inspiring views.
Dropping from Inspiration Point, Wildcat is a beautiful 2 1/2 mile curving descent to San Pablo Dam Road. Watch your speed on some of those sharp turns....
The Bears or BARTWildcat Canyon ends at Bear Creek Road and San Pablo Dam Road/Camino Pablo.
For the Light Riders, it's simple: You take a right on Camino Pablo and cruise a few miles to the Orinda BART station. Remember to bring your Clipper card or BART ticket, or bring a way to buy a ticket for the train.
Everyone else does another local favorite, and second good climb, which is actually a series of hills and rollers: Bear Creek Rd, AKA Three Bears, through the nearly civilization-free Briones Regional Park. There's a couple of big humps and a few little ones you'll climb and descend before looping back to the cityscape via the rolling Alhambra Valley Rd. and Castro Ranch Road.
Here's the authoritative, definitive, information about which hump is really papa bear, which is baby, which is momma: The definitive truth is ... it's fun to talk about as you climb them.
My own outlier opinion is that the big hill closest to Wildcat is the papa, the hill at the other end (Alhambra Valley Rd.) is the momma, and there are a couple of babies ... it's actually maybe 4 1/2 bears. :-)
If it's a hot day, bring plenty of water/electrolyte ... there is not a lot of shade and very few watering stations on the Bear Creek loop.
After you've come back to San Pablo Dam Road, The humanes take a right on San Pablo Dam road and loops back to town through the northern city route (Key Route). An option is to take a left on San Pablo Dam Road and head straight to the Orinda BART.
The stronger riders go left and come back to town by way of Pinehurst—the third good climb—which should be a familiar friend by now, since it's a return route on so many other routes. If you haven't done it before, enjoy the beauty and cool local environment of the deep, redwood-shaded canyon, but save some leg strength for the last 1/4 mile of the climb before Skyline—it's one of the steepest little sections on the route sheets ... and after a few other climbs, even the strong riders will feel it.