Seems a lot of people are depending on cell phones that they HOPE will work in the bush. What are you going to do when your cell phones gets no reception? And generally when phones get no reception they drain their batteries at a higher rate searching for a signal. Keep this in mind.
I often ride solo. I leave a map of the area that I am riding in with my wife and tell her where I am riding. I always have a whistle on my pack and carry an emergency blanket, plastic poncho, lighter, flashlight, duct tape and Swiss Army Knife.
If I ride way in the outback I have a topo map in hand, a back-up topo map in a plastic bag, GPS in hand, the route on my cell phone gps, a battery back-up for my cell and flagging tape (to flag confusing intersections on a route). Ill also carry light emergency supplies for a night in the bush if needed in addition to the items listed above.
In the last 12 years of riding the only items list above that I havent used are the lighter, whistle, space blanket and rain poncho.
The biggest thing to me is trying to ride a little tamer when alone to reduce the risks.
"If everything seems in control, you're not going fast enough."