I've visited SF too many times to count, but I had never explored the city by bike. My kids (23, 16) and I loved every minute of the 4-hour Classic tour. Here's why:
1) Our guide, Frank, knew he had a group of experienced cyclists so the pedal pace was awesomely brisk, with lots of stops along the way to hear stories, explore neighborhoods by foot, grab some treats to eat, and take pictures. Each member of our group took a turn riding at the front with Frank because he joyfully dispensed insider tips and was such good company.
2) A bike tour of SF, with a hill or two to climb, tends to attract active travelers. If you like experiencing something new with adventurous types, getting to know where they've been and where they're headed, this tour is for you. Our group included experienced skiers, National Park enthusiasts, and a couple in the middle of an epic RV road trip.
3) Certainly many cities are known for their diverse neighborhoods, but there's something magical about the Castro and Haight-Ashbury and the Mission District and Pacific Heights and Golden Gate Park (to name just a few) co-existing in the same 47-square miles. And then there are all the microclimates! (Frank will fill you in.)
Book your tour already - it's a fabulous way to spend a sunny SF day.