Environmental factors are the primary factors in determining trail impacts.
Solutions to trail impacts should emphasize managing environmental factors through initial trail design and ongoing management. Trail impacts are a complex mix of environmental, site, use, and managerial factors that combine to produce a wide range of effects. All other factors explored left most of the change in trampled width unexplained. Shade and slope are important environmental factors in determining the degree to which a mountain bicycle trail will change as it is used. Once a mountain bicycle trail is designed and constructed, shade and slope factors are essentially fixed.