Every cyclist who rides in the dark has a close call—or worse.
A car tries to make a left turn across your path, or noses out to make a right turn into your lane, or merges directly into you, or... the possibilities are endless, but one thing is for sure: the car always wins.
The number one reason? Cars rarely see cyclists who aren't equipped with a front headlight and rear flasher, so you might as well consider yourself invisible to vehicles if you ride without lights.
Sure, a cyclist can play the "I'll see the cars first, and get out of the way if they don't see me" game, but only for so long. A light dramatically increases the odds that a car will see you, and a light also means you are much more likely to see the nasty pothole, or whatever obstacle happens to be lying in wait ahead, ready to swallow your front wheel and send you not-too-prettily endo-ing over the bars.
That's not to say that a light makes a night rider infallible, either. But lights make a big safety difference in the bike-car equation.
Maria McCoy, an accomplished rider who recently took up using a bike light, often rode after dark sans lights. Recently she mentioned surprising her husband by returning home to swap battery packs 30 minutes after leaving for a ride, and then head right back out. A few years ago she wouldn't have considered—for that matter, didn't even own—bike lights, but now she doesn't take any chances.
"Lights are heavy and it's a hassle to take the battery charger along to work, but they are lighter and less hassle than a cast on my arm!" says an emphatic McCoy, who at various times has been a bike racer, bike messenger and bike commuter.
Lights are most important in winter, when cyclists—commuters, racers in training, grocery store milk run riders, anyone—battle dark roads every night. But lights aren't only for defense. Flip on a good lighting system and you're suddenly looking at a whole other half of the day to ride, albeit the moon-lit side, whether the mercury is hitting the freezing mark or short-sleeves temperatures.
Riding late into a warm summer night, when traffic is light and weather is comfortable, is a great change of pace, and night mountain biking, unless you're navigating by the stars, requires a good lighting system as well. And some climates are nearly unridable during summer daylight hours, necessitating a lighting system to be able to pedal in comfort after dark. Lights are a year-round riding accessory.