Dear Ninja Cyclist:
Get a light!!
A Night-Time Cyclist.
Really, if you’re out there after dark on a bike, you need to have a headlight. It wouldn’t hurt to have a taillight, too. But if you can only afford one (and, these days, quality LED bike lights are cheap–a heck of a lot cheaper than a helmet, and a heck of a lot more important to your safety at night), get a headlight. A headlight is much more important than a taillight.
And if you’re on the bike path, the need for a headlight isn’t lesser, it’s greater. I’m sure you’re thinking "but there aren’t any cars to squish me on the bike path." First of all, that’s not the point; it’s not just about cars. There are other cyclists on that path. And, even with a headlight of my own, I might not see you until I’m practically on top of you, if you don’t have lights. Unlike the roads, the bike paths (at least all of them that i’ve seen) are fairly dimly and intermittently lit. Just this evening I had to dodge 2 oncoming ninja cyclists who were weaving all over the path, completely unlit, and without enough reflectors to pick up my lights. And what do two ninja cyclists do when they meet on a dark path? Not to mention the pedestrians you need to dodge if you’re on most bike paths–and you can bet they won’t be lit up.
Secondly, it’s not true that there aren’t any cars–because the bike path still crosses roads all the time. And those intersections are often constructed to the standards of sidewalks, not roads, meaning that visibility of and for the cars on that road is much less. Without a headlight, they may not be able to see you until you are on the road in front of them. And, in a few cases, you might not be able to see the cars–or even their headlight beams–until you’re almost on the road.
And that, right there, illustrates why you want a headlight. The headlight is most useful not because of traffic on the road you’re on, but because of cross traffic. Many cyclists are very worried about being hit from behind by a car. There’s just not much risk of that. Even without bike lights, the car’s headlights will illuminate you long before they hit you. The majority of the time, bikes are hit by cars from the side–either crossing the street, or turning. And in both those cases, once the motorist can see you in their headlights, it’s usually a moot point: either they’re far enough away that you’ll be gone by the time they get there, or they’re so close that there’s nothing either of you can do about it in time.
Most cyclists seriously over-estimate their night-time visibility, in general. Just because you can see the cars, doesn’t mean they can see you. Some of this is due to not realizing just how much light is reflected or soaked up by the car’s window glass–we forget that just because we can see fine, that doesn’t mean that a person in a car can see equally well (the fact that you can see glass is proof that not all the light gets through it). Some of this is due to not realizing how much the headlights blind motorists to anything not illuminated by them–in terms of eyesight, the dark areas are even darker, due to the headlights.
Now, I want to address one other common explanation for ninja cycling: "I don’t need the lights to see where I’m going, and the cars are easy to avoid, because i’m maneuverable and they’re easy to see". Which is all very fine–until you don’t see someone. Like that dark-colored car rolling out of a driveway between parked cars with it’s lights not yet on so as not to light-strafe the house and wake someone. Without lights, the burden falls entirely on you for your safety. With lights, there is some redundancy so that if you mess up, hopefully the other vehicle involved will still avert disaster. Sometimes this notion is even extended to include an active desire to avoid being seen, apparently due to fears of motorists intentionally impeding travel, or even deliberately hitting them. Here’s the thing: if a motorist wants to hit you, there’s not much you can do about that. They simply have more horsepower and a big protective cage. Wasting mental effort on that is pointless. Instead, focus on making it as difficult as possible for non-hostile motorists to accidentally hit you. Honest–most motorists would rather not hit a cyclist. If only to keep their insurance premiums down.
 Okay, yes, sometimes the bike hits the car from the side. It’s still functionally the same–it’s due to one vehicle crossing the path of the other, due to being on crossing streets or because of a one of them, most often the motorist, turning. Who hits whom is just an accident of which vehicle is further ahead in its trajectory, or who manages to brake first. Oh, and I’m lumping in pulling out of driveways and other such maneuvers which, for these purposes, aren’t really any different–it’s still about crossing paths, rather than parallel paths.