I Have rented a bike here in 2011 to take a trip Sienna, radda, greve, Florence, Gimignano, Volterra, Sienna.
Beste tip! Dont look further just go to DFBike.
Why: € 80 euro a week
New bikes every year
Included: repair set, spare tires, 2 rear bags size you want, stearbag
Yes it sounds like a commercial but they have everything you need and are very friendly. I wnet there with just a ticket after looking for days on the net. afterwords it seemed to good to be throug.
If you need a digital map i can send you one to put in your watch or other gps device.