I have several friends who belong to a group of mountain bike clubs who build trails for mountain bikes on public land (both BLM & NFS) in Arizona, Utah and Colorado. They use power equipment and do lots of earth & rock moving. My question is do they need permits or other permission to do this? The public agencies (especially the Forest Service) seems to be on a mission to limit OHV and 4 x 4 access by closing roads. IMHO mountain biking does as much damage to the land as existing roads do. They are building trails all over the high country here in Colorado.