You do need to have your dog on a leash on that one. That is a bit of a drawback in that regard. The thing is you have to hike quite a bit on multi use trails. All of those or double wide, and on a bike you can haul some serious ass. So a dog off leash, might not be such a good thing. I think on the hiking only trails, you could risk letting pooch off leash. Same goes for the Elk Overlook hike from the lake. The climb is pretty steep, but it's fire road. So there is plenty of space to avoid collisions and that sort of thing. We were the only bikers who went up there anyway. Probably not a lot of two wheel traffic in that spot.
I wish the snowboarding off of 285 was better. For summer hiking and biking it is a pretty fantastic area. The S'Platte is one of my favorite regions in Colorado.