Most off-road cycling is done on public park lands and back country trails. The mountain bike industry spends a lot of time working with Federal and State agencies to ensure trails remain open to cyclists. In an effort to keep "off-road" cycling open to everyone, you should always follow the rules of the trail:
INTERNATIONAL MOUNTAIN BIKE ASSOCIATION
RULES OF THE TRAIL
Ride On Open Trails Only
Respect trail and road closures (ask if uncertain); avoid trespassing on private land; obtain permits or other authorization as may be required. Federal and state wilderness areas are closed to cycling. The way you ride will influence trail management decisions and policies.
Leave No Trace
Be sensitive to the dirt beneath you. Recognize different types of soils and trail construction; practice low-impact cycling. Wet and muddy trails are more vulnerable to damage. When the trailbed is soft, consider other riding options. This also means staying on existing trails and not creating new ones. Don't cut switchbacks. Be sure to pack out at least as much as you pack in.
Control Your Bicycle!
Inattention for even a second can cause problems. Obey all bicycle speed regulations and recommendations.
Always Yield Trail
Let your fellow trail users know you're coming. A friendly greeting or bell is considerate and works well; don't startle others. Show your respect when passing by slowing to a walking pace or even stopping. Anticipate other trail users around corners or in blind spots. Yielding means slow down, establish communication, be prepared to stop if necessary and pass safely.
Never Scare Animals
All animals are startled by an unannounced approach, a sudden movement, or a loud noise. This can be dangerous for you, others, and the animals. Give animals extra room and time to adjust to you. When passing horses use special care and follow directions from the horseback riders (ask if uncertain). Running cattle and disturbing wildlife is a serious offense. Leave gates as you found them, or as marked.
Know your equipment, your ability, and the area in which you are riding -- and prepare accordingly. Be self-sufficient at all times, keep your equipment in good repair, and carry necessary supplies for changes in weather or other conditions. A well-executed trip is a satisfaction to you and not a burden to others. Always wear a helmet and appropriate safety gear.