http://www.banyantreebiketours.com/
Best experience I had in Bali. 10/10. They accommodate all age groups. I did the tour with my mother and we both loved it. Breakfast is included in the price. You finish up with a lunch at the owners house prepared by his wife. Again, included in the price. At the end of the tour we vowed that we would fly to Bali again one weekend just to do this tour again (We enjoy a 3.5hr flight time to Denpasar here in Perth).
Have a look at reviews on TripAdvisor - some great pictures too! The scenery is fantastic too.
Have a pleasant stay in Bali!