When you are hiking and there is a biker approaching from ahead, your first thought is to get the heck out of the way so you don't get mowed down... But did you know, you actually have the right-of-way? Bikers are supposed to yield to hikers. I'll be honest though - I don't have the heart to mess with a bikers momentum! A lot of the trails here are up mountain sides, I'm not going to make a bike stop his climb when I'm walking down hill. It has got to be hard to get going in the first place! So techneiclly the biker must yield, but courtesy on the hikers part is appreciated. Picture from Biketrails.com.
What if your hiking and are approaching a horse from the other direction, or a horse is coming up from behind? In this case, the hiker yields to the horse. A biker would need to do the same as well. I have heard It's also a good idea to turn away from the horse as they are passing by as not to spook them.
I wasn't sure about what happens when I biker needs to pass a horse, so of course I did some Googling. From what I could find, the biker should slow to a walking pace and establish verbal contact to the horseback rider for instructions. The article where I got this information also says that horses don't often recognize bikers as human because of their gear and movement. Also if the horse has a bow tied in their tail - it means they like to kick ... but just becuase they don't have a bow in their tail, doesn't means they wont!
I'm sure a lot of you out there know this stuff - as many geocachers hike, bike and ride horses. If you have anything to add please leave a comment!!
In addition to the previous link in this post, I also used this site for more info.