• when a driver sees a flashing rear light AT NIGHT, it is hard for them to judge how far away it is, and how fast it is moving. A steady light is much more effective for an approaching motorist.
• during daylight, when ambient light lets you identify the distance, a flashing rear light is more effective for catching a motorists initial attention.
• you should not cycle with only a very bright, flashing front bike light AT NIGHT. This also makes it hard for oncoming road users to judge where you are and how fast you are coming at them.
• daytime is definitely the time to flash those bike lights.

REAR LIGHT

• at NIGHT - the best bet for maximum visibility is to have two rear bike lights (one steady and one flashing) at night. If only one, a steady light.
• during DAYLIGHT - a flashing rear light is best.

• at NIGHT - a steady light
• during DAYLIGHT - a flashing light