Somehow this has been forgotten, but in the pecking order of trail users, bikes are last. That means when you see a hiker, slow down or stop and let them pass. When you see horses, which are easily spooked by bikes, come to a complete stop, get off your bike and off the trail, and communicate with the equestrian about how best to proceed.
Yield Some More
Uphill traffic always has right of way. If you’re blazing down at high speed and come upon another rider, it’s your responsibility to slow or stop and make plenty of room for that person to continue on their way. It will be easy for you to restart (thanks to gravity), but if the person climbing has to stop, he or she may be unable to get going again.