Not to burst anyone's ambitions to cycle down Halekala, but I grew up on Maui, and I can't tell you how many times I went early to see the sunrise and came down to see there was a dangerous cycling accident. The tours tend to be made up of all cycling abilities, and the angle of decline with the constant switchbacking makes it treacherous. Just a note of caution to be careful when doing this ride.

If you want some fun on Halekala non-cycling related, I'd suggest doing the zipline tour! Not as much exercise, but there aren't any tourist drivers to deal with.