It's posted right on the sign at the entrance of Phil's Trail: no horses, no vehicles.
But there's one group allowed on even the most popular trails that could surprise you: hunters.
Hunting season is here, and many areas around Central Oregon are fair game.
Most of the mountain bikers NewsChannel 21 spoke with Wednesday near Phil's Trail didn't know hunting was allowed in the vicinity.
But Erleen Sims of Roseburg has been riding Phil's Trail for years -- and at this time of year, she's extra-cautious.
"I just saw a bow hunter out here yesterday," Sims said. "It's a little bit scary, and then I thought, when do the guns go off?"
During hunting season, hunters are allowed on most public land anywhere outside city limits.
Oregon Department of Fish and Wildlife Biologist Corey Heath said it's all about common sense and courtesy.
"Make yourself visible, wear bright-colored clothing," Heath said. "And if you encounter someone hunting, just say hi and be cheerful."
And while you shouldn't be surprised to come across hunters on trails, many hunters prefer less traffic to stalk their game.
"If there's a really popular mountain bike trail, I doubt there's going to be people out there looking for cougars or bears or whatever they have tags for," said avid hunter John Diefendorf.
Defindorf said he not only looks out for bikers and hikers -- he has to be extra-watchful for other hunters.
"Just need to be sure of what you're aiming at and shooting," he said.
It's about making sure your target has four legs -- and not two wheels.
"You guys (have) got acres of space around here, so I don't think there's any shortage of hunting areas," said one mountain biker visiting from New Zealand.
And It appears people are being safe in the High Desert's woods in their mix of uses. ODFW officials told us they haven't heard of any recent accidental shootings in popular recreation spots.