I am going to San Francisco next week. Is it possible to rent a bike and go across the golden gate bridge?

If anyone knows how much it is to rent a bike in golden gate park please let me know. Also, let me know if there are any must-see places in the city that I should go to. I will be staying around fisherman's wharf. I would like to spend a couple days sight-seeing around there, then spend a couple days elsewhere around the city.