The Bay Area is a great place to explore by bicycle. When you've got no wheels in the City, it's generally not a problem. But there are times when you just need that extra boost. Fortunately there are many options beside the ever-present Bay City tourist bikes. Even if you're a tourist, you can find bike shops offering high-end bikes and in some cases even private tours.
The best one for on-the-fly rentals, BikeShare Bay Area, just launched in August. There are now over 30 bikeshare stops in the east side of SF where you can literally turn the key and drive off on your own fully maintained, eco-friendly bicycle. Membership starts at $88 per year, or you can rent a bike for the day for as little as $9 per bike.
Although helmets are not legally required for adults in California, many riders feel more comfortable wearing one. Many bike shops sell them or will rent a helmet for about $5/day.
SAN FRANCISCO'S TOP RENTAL BICYCLE SHOPS