You should always run a minimum of two lights on your bike while riding at night—a front-facing light to illuminate the road ahead and a rear-facing taillight so drivers behind can see you. Your front light should be white, bright enough for you to see any upcoming obstacles, and set to the solid-beam option. Most good nighttime front lights range from 250 to 2,000 lumens (in comparison, a car headlight is usually 700 to 1,200 lumens). “For a light that is designed to see, many riders are comfortable mountain-biking at about 700 lumens, but 1,000 lumens is what I really start recommending as the minimum,” says Alex Applegate, the marketing manager at Bontrager, a maker of cycling apparel and accessories like lights. “ If you are commuting on the open road and using the light to see, I would use the same recommendation. In a city setting with more ambient light, you can get by with less.”

Your rear light should be red and ideally pulsing, and it only needs to be bright enough for other cars to see you. Your rear light only needs to be 50 to 100 lumens—much less powerful than your front light. Remember: it doesn’t need to help you see, just be seen.