I was on @ 5:45 and off by 6:45 for an easy 6 miler with great scenic views and some random flora, hub caps, etc. The path I took which was where this app dropped me on the map was a rolling paved bike path with various terrain off shoots. I noticed 3 or 4 branches into other dirt roads, horse trails, etc that I might go back and try for a bit more adventure. I'm guessing the other photos are from shimmying down in the canyon which might be fun but I kept thinking flash flood and your toast. Temperature was fine for this San Diego guy but I wouldn't want to be out here after 7:30am in July.
Since it was not evidently clear to us ill post here so that others know this is primarily a bike path through open desert. The whole way is paved. Based on the photos we assumed this hike was through a canyon. The canyon area is accessible near the river mountain path but it would require a decent bit of scrambling especially after heavy rain last weekend. We couldnt get down as we had our 2 dogs with us. Also be sure to bring sunscreen and plenty of water as this path is direct sun with no shade.
Can't find a link for the entire 35 mile River Mountains Loop so I'll post here. We spent a week in Vegas and rented hybrid bikes. We completed the RMLT twice (CCW both times) in that week, about 4 hours or so each time. Awesome, great rides. Very little traffic on the trail itself, and very few road crossings. Couple of the grades were a bit much for this flatlander, but the views and the workout were great.