Trail use is usually split into three groups, hikers, mountain bikers, and equestrian. Some trails don't allow horses, some don't allow mountain bikers, and hikers usually have free rein. When trails aren't multi-use (open to all three parties), restrictions on trail traffic are sometimes debated or disobeyed. When trail access suddenly changes, outdoor enthusiasts can discover they have trouble sharing.
The Los Angeles Times reports that in 2007, multi-use signs were posted on trails in Placerita Canyon Natural Area that had previously been closed to mountain bikers. When bikers began riding the new routes, they decided they liked them. Some hikers and equestrians decided they didn't like the new bike traffic and complained. In an Office Space moment, the L.A. County Department of Parks and Recreation "fixed the glitch" and took down the multi-use signs. After four years of access to the trail, mountain bikers were once again banned. As it was in the past, only horseshoes and hiking boots are allowed on the trail, and mountain bikers feel cheated.
The Los Angeles Times also notes that mountain bikers may lose access to other trails in Southern California as the U.S. Forest Service reevaluates trail access. If fewer and fewer trails allow bikes, and mountain biking stays popular, the remaining mountain bike-friendly trails in Los Angeles could become overcrowded by mountain bike traffic.
It is sometimes argued that mountain bikers should not share trails with equestrians because speeding riders can spook horses. Environmental impact studies have shown that horses do more damage to trails than cyclists, so why are bike riders often the first to be banned? Trails in Placerita Canyon Natural Area and other parks are on public land. While not every trail should be multi-use, it is important that the governing bodies balance out interests and make room for each form of recreational use as they ensure the preservation of the land.