I've been instructed by my doctor to limit my hiking to less than 1 - 1.5 hours at a time and keep my heart rate less than 140 bpm as I am recovering from some surgery. All of my "short" local favorite hikes (Tomales Point, Johnny's Pond @ Del Valle, Mission Peak) exceed this restriction either due to elevation change (which puts me over 140 bpm) or distance. Any recommendations for beautiful quickie hikes in the Bay until I'm back to normal? I'm willing to drive for awhile just for variety, so maybe anything within 2 hours of SF? Thanks in advance for your advice - spending time on a machine in the gym when I could be outside is driving me crazy!

You can drive to the summit of Mt. Diablo and do some short hikes from there. The view is very nice.
Hope your recovery goes well.

ALamare Falls ? I have done it many times and don't recall a lot of elevation changes. (on the coast)

There are many great suggestions at the following site:

http://www.bahiker.com/index.html

There are many trails in Marin that are not strenuous including ones on Mt. Burdell and Mt. Tam. The site that I mentioned sorts the hikes by difficulty so you should be able to identify which ones will not PO your doc

Bald Mountain, beneath Mt Umunhum in the Santa Cruz Mountains is very short, but it's a nice walk with great views.

http://www.summitpost.org/mountain/rock/154539/bald-mountain.html

See: East Bay Out by Malcolm Margolin. Great guide to the East Bay Parks.

Any recommendations for beautiful quickie hikes in the Bay until I'm back to normal?

For beauty, you can't miss with Muir Woods. Big redwoods and fern gardens are the Bay Area's best for nature. Although you have an entrance fee, then the many tourists. Big Basin also has some good trails, and I would suggest bike trails as you can find them. I like urban hiking in SF, there's Twin Peaks via Market Street, and we used to do a loop about the city center, to the Civic Center, Wharf, Chinatown, North Beach, Financial District, and then the Embarcadero (5 miles).

I only go for uphill exercise, namely peaks (bumps), but the Bay Area is great for walking. If you suffer some problem from exertion, medical help is right there. And if you bit off more hiking than you can chew, mass transit is excellent (by most city standards) to get you back to your car or home.

I just got back from a couple of days out in Point Reyes, always lovely, but the most of the good stuff is out of the range of your curfew.

Working down the list of EB PARKS
http://www.ebparks.org/parks/maps
I'd recommend:

Black Diamond Mines
Briones
Coyote Hills
Huckleberry/Redwood/Sibley/Tilden/Wildcat (and everything else on the ridge)
Lake Chabot
Las Trampas
Miller/Knox
Point Pinole
and there are plenty more.

Lafayette Reservoir
http://www.ebmud.com/recreation/lafayet ... ation-area
And more EBMUD trails here:
http://www.ebmud.com/recreation/trail-u ... bay-trails

If you're in San Francisco, San Bruno Mountain State Park is a surprisingly pleasant and convenient place to spend a couple hours strolling around:

http://www.parks.ca.gov/?page_id=518

Edit - And don't forget Crystal Springs Reservoir ...

Lots of stuff in Santa Cruz Mountains that would qualify...

Mellow loops in Big Basin
Russian Ridge Open Space
El Corte de Madeira Open Space (Tafoni loop always fun)

Enjoy!

Most of these recommendations are good.

So far as the East Bay goes, Lafeyette Reservoir is flat and sometimes paved and sort of boring.

Tilden and Wildcat and Sunol, etc., are good ideas, but will get really muddy once the rains start back in. Sibley tends to be a bit rockier and drier.

In the North Bay, Ring Mountain (above Tiburon) offers some nice easy hiking with killer views. Plus you can fondle the boulders as you go by to help remember what climbing feels like. Go on a Sunday, and if you finish early, you can drive down to Tiburon and grab an early table at Christophe's. Mmmmmm, cassoulet . . ..

If you start to get that white knuckle, Bay Area-bound feeling, then head out 120. Knight's Ferry, Red Hills, and the top of Table Mountain would give a bit of variety and help you feel like you've gotten out of town.


Edit: I just learned that Christophe's has closed. RIP

Right in SF there's Land's End, Golden Gate Park, Crissy Field, Fort Funston, Ocean Beach - all meet your criteria. A longish (10 mil) urban hike is to start at the Ferry Building at the Embarcadero, walk north along the Embarcadero to Ft. Mason, head west through Crissy Field, up and across the Golden Gate Bridge, down into Sausalito, and take the ferry back to your starting point. Just across the bridge there's lots of hiking in the Marin Headlands. Also the trail down to the beach at Tennesee Valley is nice and fairly short, as is the hike up to the scenic overlook. Mt. Tam, Muir Woods, and Pt. Reyes have already been mentioned, but China Camp State Park and Bodega Head haven't, and there's some nice shortish hikes at each.

If you don't already have it, get a copy of Tom Stienstra's California Hiking - it has several chapters devoted to the Bay Area. After living here 13 years and doing an average of at least one hike a week, I still haven't checked out all of the Bay Area hikes in Stienstra's book yet (though I have done some hikes many times). The book includes distance, predicted hiking time (which I find to be an overestimate unless you are pretty slow), his subjective opinion of the scenic value, and his level of effort rating from 1-5. Anything he lists as 1 or 2 are very gentle; I just took my 78 yr old father on a hike rated "3" and he never got out of breathe (though Dad's pretty spry for his age).