As a serious S.F. Bay Area cyclist for over 40 years I approach any guidebook to my "back yard" with a certain degree of skepticism, as in "What new can you possibly show me?" I was delighted to find that Ms. Jackson did indeed show me some new mountain biking delights I'd overlooked, but along the way I learned even more new tidbits about what I supposedly already knew. Almost every featured ride has "enrichment" far beyond the necessary trail and topographical stats. No doubt the author learned things from her literary predecessors, which is as it should be, but there is also no doubt she has written the currently definitive off-road guide for mountain bikers of this region. The miracle of the S.F. area is that 5 million people can live so close to so much open space. It is no mean feat to review it all personally, provide directions that are simultaneously explicit and open ended, and simultaneously appeal to the first time rider and a "show me" old time rider such as myself. But Ms. Jackson has done this much, and more. I mean her guide book is not only that, but a fun read as well. Imagine!