Don't know if the moto rider was an adv'er or not. I was riding with a group of mountain bikers and we were nearing the end of our day. We were riding down what google maps shows as Forest Service Road 5S05, lat/lon 33.701029,-116.690533. The motorcyclists (2 of them) were on Hondas (an XL650 and an XR650) and were riding up. I was about 30 seconds back and didn't see a thing. The road turns and is bordered by high chapparal zone brush on both sides. Moto rider is on the street legal XR650 going up at what he estimated was 20 - 25 mph and the mtb'er was going down at what I'll estimate as about the same speed. Neither remembers the impact. When I arrive, the moto rider is standing and the mtb'er is lying unconscious on the ground. The bike rider is bleeding from a head wound, his breathing is labored, and his skin color is bad. But he regains consciousness after a couple of minutes though his level of consciousness is way reduced. Luckily, there is good cell coverage and 911 calls go out in a minute or two. I had a Delorme inReach and used the 911 function to send out an alert. I got a call back within about 10 minutes from the IERCC (don't know what it stands for but it's who gets the wheels turning for rescue). It turned out in this case to not be necessary as the 911 operator was able to get our location within yards just by the cell phone call. The CHP helicopter flew in and landed a short time after the CDF paramedics arrived by driving in after cutting the chain on the gate on SR74. I'm guessing within 30 or 40 minutes of the crash. The pilot had a big brass set and landed at the turnoff to what I call the meadow section which heads west back to SR74. The bicycle rider was evacuated via the helicopter with a broken femur, decreased level of consciousness (though much improved by this time), and other lacerations. While all this is going on, the moto rider starts getting light headed and nauseous; and complains of moderate head and chest pain. The paramedics decide he should be transported. The rider (sorry I didn't get his name) doesn't want to go I think partly because he didn't want to leave his motorcycle there so I offered to ride it back to the highway, and then he agreed to be transported. The evidence is not conclusive beyond a reasonable doubt as to who if anyone was on the wrong side. Neither party remembers the moment of impact. I've thought about riding my motorcycle up there but didn't want to deal with all the mountain bikers. Now I'm pretty darn sure I won't ride my motorcycle there, at least on the weekends when it's pretty darn busy. That and the fact all the single track is only for hike/bike/horses. I hope all are doing better.