My fiance, mom and I rented 2 road bikes and 1 hybrid comfort bike in mid October.
The comfort bike was perfect for my mom, who doesn't ride much.
Initially, the road bikes were having some trouble with changing the gears, but after a little attention from the shop attendants, they worked perfectly. They also installed SPD pedals for us - for all of you serious riders out there. We made online reservations, and so we got better rates, than in person. The bikes performed excellently and made it all the way to Tiburon (back to SF by ferry).
We highly recommend using San Francisco Bicycle Rental for you needs.