I ride on the road and use a dynamo setup. It stays on all the time. Surprisingly the headlight is bright enough for me to see the road at night and people starting from a stop in daylight to see me. About four years ago someone texting on a cell phone nailed me with their mirror in daylight. I looked up bright tail lights on the web and found the Dinotte daylight visible taillight. The close calls went away and I can watch in my mirror and see them moving over from a distance.