The way points of this bicycle route:
Take BART to the Orinda station. From Orinda BART station, take Moraga Way southbound (you have to loop around the station a bit, follow the signs).
Moraga Way is commercial for a couple blocks, then is wooded and residential, with a decent shoulder and a basically well-behaved stream of traffic. The only thing to watch out for is cars coming out of the blind driveways. Moraga Way slopes slightly uphill for most of its length; it's not steep but it can be tiring. Don't push too hard, especially if you plan to do one of the intermediate or advanced rides.
After about 6 km, Moraga Way descends into a business district in Moraga, then ends at Moraga Road.
At the intersection of Moraga Way and Canyon, turn right onto Canyon. Canyon is residential for the first km, then rolling and wooded until it ends at Pinehurst after 3 km.
Turn right on Pinehurst.
Pinehurst is wooded and pretty (see above, left). It slopes gradually uphill until you pass the city of Canyon (which consists of a post office), then becomes twistier and steeper.
The steepest part is the hairpin (above, right); if you get past there, you'll probably be OK.
After 6 km and a fairly significant climb it ends at Skyline Boulevard. Turn right on Skyline Boulevard (look at the street signs, the intersection is confusing).
Skyline is a residential road populated by ex-Berkeley liberals who have sold out and made a million bucks. It's wide and there's little traffic. If there are no clouds there will likely be some stunning views of the bay--if there are clouds it's likely you will be in them.
If you continue straight, you'll wind up on Tunnel Road, which descends into the Rockridge area.
After about 5 km of descent, the road will end at an unmarked T intersection; turn left. After you go around a bend, take a right turn to go over the freeway, and then a right turn again on the other side; this will put you on Old Tunnel Road, a fast, mostly straight descent into north Oakland.
Old Tunnel Road ends at a strange intersection with Broadway; turn left on Broadway. Broadway can have heavy traffic, but it shouldn't be too bad on Sunday afternoon. It has a fast, straight descent soon after we get on it, then it continues slightly downhill. If you go right you end up on Tunnel Road into Berkeley and can take Claremont to Rockridge.
After about 3 kilometers, College Ave will be on your right; turn right and take College back to Berkeley.
BART or continue on to Berkeley.