I've only needed it as "backup" on classic bikes with vitage incandescent bulb dyno lights as a stand light, or when a bulb went out.
They're also useful to supplement functioning dyno lights with the flashing function in certain low visibility conditions.

I did have a bearing in a Sanyo hub go bad, ruining the hub, but I don't count that as a lighting failure per se.

I would count that.

The reasons I don't is because the bearing failure didn't affect the lighting, it still functioned, but the bike was unrideable due to the bad bearing and damaged axle.

I'll throw in my usual vote for the Cygolite Metro series. I have 2 different models (500 and 300) on 3 different bikes and have been pleased with them.

Speaking of Cygolite, the battery in my Hotshot tail light wore out after about two years, maybe more. They don't sell replacement batteries on their website, so I sent a note to their support department to see if I could buy a replacement. I sure hope so.

Rechargeable Li-ion batteries start to lose capacity and go bad after about three years. My understanding is, this is true even if you don't use the light. It makes me wonder how long a light with a built in battery was sitting around before being shipped to a customer.

[MENTION=6007]2manybikes[/MENTION], that's true. In my case, I'm not saying I got a bad deal. I got about the right lifespan from the battery, and I should expect it to crap out now. I just want it to be replaceable, and I hope it is.

As you point out, there is a risk of buying a product with a LiIon battery that isn't fresh stock, but I don't think that happened with me. I'm happy with how it lasted. It was between two and three years.

If it is replaceable, I'd love to hear about it. Hopefully you are right.

Modern bike has the hotshot for $23.49 and free shipping. I have one coming up on 3 years as well. [MENTION=152773]noglider[/MENTION], I'll be interested in the reply to your email.

At $27 new from Amazon, I'd be shocked if it is. Don't hold your breath.

J.

Not inexpensive but the Niteflux Whitezone is IMO amongst the best "be seen" lights.

The most effective light I can recommend from my 15 years of urban bike commuting isn't a bike specific light at all. I use a fairly cheap set of front bar light and rear flasher but for riding thru dense traffic with lots of random light pollution from retail windows and such I've taken to dangling under my saddle a low cost LED flashlight set to strobe . This illuminates my frame and my furiously peddling legs and is visually disruptive in the idea way for making an impression on cell phone distracted drivers. People have commented so I'm pretty sure it doing the job - that and still being alive and uninjured. Gotta switch it off on the dark back streets of course because its strength is its weakness, its damned annoying.

I get your point. And I don't agree. For $27, I'd like it to remain useful for more than two or three years. Most of it is fine. The molded plastic is good. The LED is fine. The LED and the battery probably made up more than half the cost of manufacturing. Let's say, for argument's sake, each makes up 3/8 of the cost (and therefore value). So I should throw away 5/8 of a light? I'd be willing to pay half of the price, maybe even more, for a battery. I'd be willing to risk breaking it by taking it apart, too.

Hmm, this gives me a thought. If they consider the light to be trash, I'll open it and see what kind of battery it is and if I can find another.

Don't think of it as bumpy, think of it as adventurous!

I was just thinking about that. Good idea. Nothing to lose.

So as not to keep the thread drift going, I have my own thread about the Cygolite battery replacement.

Unrelated, but I love the "Hyperbole and a Half" avatar.

Thanks, ThermionicScott; it reflects the level of my brain function, particularly today. I am utterly baffled at why I stayed up so late last night after a long hike. Danged Walking/Talking Dead.

...zzzzzzzzzzzzzzzzzzzzzzz...

Yeah, which is why so many people who ride at night recommend a Flashing front light, which does attract the mind of the driver.

The motorcycle rider can get a similar effect by weaving---in fact, that is what weaving does, but I am not about to start weaving across the lane on my bicycle. I have a flashing light which simulates a moving object and breaks through into a driver's awareness.

Motorcycle rider would do well to flash his lights instead of weaving, I'd think.

I'm surprised no one has mentioned the Cateye Volt series.

Whilst there is the 150 & 200 Lumen models, I prefer to start with the Volt 300 and up.

I have two Volt 300's on my handlebars and a Volt 800 on my helmet.

The Volt's have a daytime flash, which brings in the light's highest lumen output.

So I like using the Volt 800 daytime flash during the day.

I will probably acquire their newly released Volt 1600 in the New Year.

I strongly disagree. Both from theory and from personal experience. Flashing light works fine in daytime. In the night it makes it harder for the driver to judge speed and distance of the cyclist. It also helps driver catch the off phase of the light when checking for cyclist - cyclist's narrow profile and the fact that it can be blocked by any land post or even car post that holds the windscreen - all make it important to stay visible all the time. That is why I'd never recommend a flashing light for night riding. Haven't noticed it helping even as a backup to a steady light.

What I've been doing the last week is using my Cateye on the bright level, not flashing, and the helmet light flashing. I'm still considering a brighter light, but I don't like that the battery life is about 300 charges (according to Cateye on their Volt series). I like battery lights, just for the longer life span, less frequent charging. I'm also thinking to get a safety color long sleeve jersey. Once it's cold enough I'll wear my blinding Pearl Izumi jacket.

Good One:
https://www.youtube.com/watch?v=vs6YZk1QZdM

That battery life is common for almost all lithium-ion batteries. It's a function of the chemistry and engineering of the battery cell. If you stay away from proprietary batteries like the Cateye and Cygo, replacement batteries are fairly easy to find and relatively cheap. The Magicshine clones that you find on Fleabay and Amazon for about $20 use 18650 Li-ion cells in a 2s/2p (two in series/two in parallel) configuration and a fairly standard cord that are around $10 to replace.

If you want or need more run time, you can get battery packs that use 26650 cells for about $20 in the same configuration. They have about twice the run time of the 18650 cells. I get 2 to 3 hours of run time on the smaller cells and 4 to 6 hours on the larger cells if I run my lights on high. Personally, 4 to 6 hours is more than I've ever needed on a night time ride.

Having recently rediscovered Sigmasport for computers and lights, I'll put in my vote for the Buster 600 (BUSTER 600). At $99 it's more than the magic shines of the world, but less than L&M, NiteRider, etc. My bias is for a self contained light, meaning no cords to separate batteries, and this fits that bill. The Buster is aluminum, so nice and rugged. It's well sealed from water. It has a good beam pattern, good runtime (2 hours at 600 lumen, 5 hours at 250, 11 hours at 110), good attachment to the bike. It also has 70% and 30% battery level indicators, so I know well in advance if I need to switch to a lower output to conserve energy. Just a great light.