According to this article, more and more mountain bikers are being attacked by dogs in the Western US and in one case a woman needed 60 stitches after being attacked by two canines near Vail, CO. Most of the dogs involved are sheep dogs like Great Pyrenees who see mountain bikers as a threat to their flock. Sheep dogs are trained to fend off predators like coyotes and mountain lions and to them, a fast moving mountain bike can look like a giant jungle cat (horses are often spooked by bikes for much the same reason).
The rise in incidents can be tied to the increasing numbers of mountain bikes venturing into remote grazing areas where sheep dogs are likely to be working. Some have suggested posting warning signs on trails where sheep dogs may be encountered while others say sheep dogs shouldn’t be allowed anywhere near public trails. It may be possible to socialize the dogs to ignore people on bikes, though some breeders have argued this can reduce the dogs’ ability to do their intended jobs.
If you’ve ever been chased by a dog on your bike it’s not a great feeling (seems to happen to me fairly often on road rides, though rarely on the trail). And while most dogs mountain bikers will encounter on the trail are of the friendly, family-dog variety, it’s important to be alert and keep your distance from working dogs like the Great Pyrenees. Have you had an encounter with a sheep dog on the trail? We’d love to hear your tips for staying safe in the comment section.