Cycle lamps with a filament bulb and LEDs. Cycle lamps are a legal requirement for road bicycles when ridden in the dark and have a long history. A white lamp is required for front and a red lamp to the rear. The lamp must be attached to bicycle frame. It must be marked as conforming to BS6102/3 or an equivalent EC standard. Flashing lamps, sometimes used in addition to the red at the rear of the cycle, must emit at least 4 candelas or 48 lumens. Only LED lamps can flash. Both lamps are 3 volt but the filament bulb requires the more powerful C batteries than the AAA batteries used by the LED lamp. Most lamps are now LED.