Mountain bikes are vehicles, and like all vehicle access, Nadia White and her partner got into a landscape they probably wouldn't have if they had to walk (HCN, 11/14/11, "Food and friendship, fossil-fuel free"). That's what happens when someone uses mechanical advantage to further access, and like all motorized and mechanical access, it degrades the experience, fragments the landscape, and displaces and harasses wildlife.
And since when are mountain bikes manufactured, shipped and sold in a carbon- or energy-free manner?
Brian L. Horejsi
Calgary, Alberta, Canada