At night I use a helmet and handlebar rechargeable light of same mount. I rotate the freshly recharged light to the helmet as it is my primary. Since it is on the handlebars I can see when the older charged light is finished. I point the helmet light at door level of drivers that might pull out in front of me. I flash them on a ~3 second period. On the rear of my helmet I have a Serfas TL60 red LED which I run in flashing mode at night and when I take the lane during daylight.