I would rate the level of difficulty for biking down Haleakala Mountain a 6 or 7 (1 being very easy and 10 being extremely difficult.) It wasn’t strenuous at all, as I was going downhill 99% of the time. However, the first 3 to 4 miles of the trip were pretty scary, as the road was windy and narrow, with cars zooming by frequently. The drizzle and strong wind at the top of the mountain made the ride more challenging. After passing the initial 3 to 4 miles, the road was wider and the ride became more relaxed. The scenery along the way was beautiful, and the air was filled with the refreshing smell of flowers and grass. I also saw several rainbows while biking.
Maui Downhill, the tour operator I used, did a great job ensuring our safety. The bike leader was in the front and the van driver following us constantly watched out for the traffic, so I felt pretty safe.
The only complaint I had with the tour was the breakfast. The website said we would enjoy breakfast at the "upcountry’s finest restaurant." The place they took us to, however, was a little bit better than a Denny’s. Anyway, I was so hungry, I did not care if the breakfast was gourmet or not. I would suggest travelers pick the less expensive tour that does not include breakfast. Save the money to spend on a better breakfast.