I also believe that Mountain Bikes cause a problem due to the distance that they cover. In England the hiking club is much more organised. We do have the sierra club, but they are much more diffuse, they get involved in other sports as well, besides hiking. Here, I think Hikers are at a real disadvantage to the equestrians, who are much more heavily organised and to the bikers who are promoted by the people who sell bicycles. Its now getting hard to buy a non-Mountain Bike.
Many areas have all kinds of management problems.
In the Kalimi State Park, a whole trail was constructed illegally by Mountain Bikers. The park had to take this trail apart. They have rangers up there with radar guns now because they have had many problems with people getting hit by bikes.