I booked a cycling tour with Bali on Bike via their website and reply was very prompt.
They do tours in groups of up to 20 (with 2 guides). Do note that there are many bike companies such as this, and there are also various routes to take, with different distances. The one I took started at 9am sharp (pick up at hotel) and ended by 3pm+ after an afternoon lunch at the owner's house. Free water/umbrella/raincoats were provided.
On my tour I was the only customer and Mun (pronounced "Moon") was my guide for the day. He was young, energetic, and engaging and I thoroughly enjoyed my trip, even on the car ride up the mountains. His speaks very good English (as compared to 2 other guides/drivers I had) and I had a great time.
Keep up the good work!
Visited December 2013