Actually, that already happened. I was coming down the Mnt. Lukens/Haines Canyon on my SC Blur, closer toward the bottom, coming down hot, came around a long turn, and saw a large animal coming up the fireroad. The encounter lasted about 15-20 seconds. I saw a white chin at first. He didn't see me at first. Seconds later, he saw me, turned around, then I saw the long black tipped tail. He took 2 hops down the road and a third down the side towards the creek. I clearly remember it's face, the tail, the long body and especially how the shoulders were and the movement. He was the size of a large dog. I was only nervous after the event as it happened to fast.