I have a large solid, car type rear light on my Guru, which is standard equipment and required in most European countries. However, when I am riding early in the AM, in the real dark (fall/spring) I also add a blinkie, attached to my rear bag or my back. I keep my front light on solid until it is clearly dawn and the sky is all light. Then I might keep it on flashing for awhile after that. In the fall, actually starting in late August, I will use my front light on flashing mode if I am riding in the late afternoon, as I live in a very shaded area and the shadows are horrendous. Sunset might not be for 2 more hours, but I have been driving home from work and have passed many, many cyclists who are almost invisible.