I would like to put in a plug for a relatively new operation (altho. the owner has had several years experience as a guide with a couple of the Ubud companies) This tour is called Banyan Tree Cycling. As anyone who has spent any time in Bali would know the banyan tree is a sacred tree and also a wish fulfilling tree. We would like to wish Bagi the very best success with his new company. The time we spent on the banyan Tree cycling tour was the highlight of our holiday in Bali. We learned so much from our guide- he revealed Bali to us, not only through the things we saw - probably much the same as any of the other tours , but also through the things he told us , his English is excellent and he is passionate about his people and Balinese culture.
This is also an "eco- tour" as Bagi is working with the farmers we visited to instigate organic farming so the money spent for this tour helps a lot of local people. He has a little promo on www.banyantree.wikispaces.com
One last thing the tour can be enjoyed from one of the back up vehicles if you don't want to cycle, you would enjoy it just as much.