Lighting Your Bicycle

[Simple Nature]

I received some very similar brackets as those on the dually lights in that image. They are cheap and seem to hold a flashlight quite well. Here's the link to the ones I got:
http://www.kaidomain.com/product/details.S004336
You just can't beat that price

As for the "18650" batteries, yes they are the typical batteries used in the laptop computer packs with a few noteworthy caviats:
1. Computer battery packs have tabs that are spot welded between batteries. The only real similarity is the size, and the fact that their technology is driven by the laptop industry.
2. You can buy the basic battery or you can buy the "protected" battery. The protected batteries protect the batteries from shorts and over charge, and over discharge. Li-Ion does not like to go over 4.2V or under 2.75V as a general rule.

When switching to 18650 technology, don;t be fooled. The MAX... capacity is 3100mah. And that is only if you are willing to spend nearly $15 per cell today. 2600mah is quite common but you want to know that the cells are quality. Sanyo and Panasonic are still the leaders in this industry. Know what you are buying or you might just get left in the dark... literally.

Same with chargers. Some chargers actually make these batteries unsafe. Unless you have quality products validated over time, yiou never want to leave these things charging unattended. I go through a regimen every time I ride and I make sure to have all the batteries freshly charged by the time I go to bed.

I can recommend one brand which is XTAR for both batteries and chargers. Locally, there is a seller of genuine Panasonic 3100mah protected cells, Callie's Kustoms, who I can highly recommend. This seller is in Cornelius if you wish to contact him. http://callieskustoms.com/CalliesKustoms-Batteries.html

Other than that, you can buy XM-L T6 flashlights for around $20 from the orient and a bit more on ebay. Just be aware of the real numbers when you buy. There are ratings for the emitter (pretty much constant when accurate) and the actual performance of the light. You rarely ned a full 900 lumens for night riding, and even daytime flashers are a bit overboard at 900 lumens. It is mostly a matter of runtime. 900 lumens will draw 3 amps at 3.3V. There is some overhead in the circuit so you can say maybe 80 efficient. When comparing 900 lumens in practice to say 450 lumens, most of you will barely notice the difference... but the runtime literally doubles. I ride with 200 lumens at night quite comfortably.

3 common LEDs you will see referenced are:
XM-L T6
XP-G R5
XR-E Q5

The real numbers are
900 lumens at 10 watts
450 lumens at 5 watts
and 240 lumens at 3 watts.

Wattage will tell you runtime when you do the math. A 3100mah cell holds 11.5 watts. With efficiency factor, this says an XM-L will run for about 1 hour, and XP-G about 2 hours, and a "Q5" about 3 hours all on full output. Fast flash is about 50% duty cycle so this doubles the runtime.

Having said all that, most XM-L flashlights only run at around 2 amps. This is good for runtime but don't expect the full output. Again, this is a good thing. One XM-L flashlight I bought was only 1.5 amps (5 watts). It all depends on the manufacturer as to what electronics they put in the light. All the advertizers lie!

As for beamshape, I totally agree. Flashlights are designed to focus light into a fine beam. This may not be what you want for a bike. If you want to be seen, you want a wide beam, and for night rides/commutes, you want at least a road width of light. The "Q5" lights are very poor in this. They have a very sharply focused beam with little "spill". Both the XP-G and XM-L typically have lots of spill. Oddly enough, the poorer the make of the flashlight, the better is will work for a bike light.

Please feel free to ask for more information.

[wsbob]

Simple Nature...very nice informational write-up.

"... As for beamshape, I totally agree. Flashlights are designed to focus light into a fine beam. This may not be what you want for a bike. If you want to be seen, you want a wide beam, and for night rides/commutes, you want at least a road width of light. The "Q5" lights are very poor in this. They have a very sharply focused beam with little "spill". Both the XP-G and XM-L typically have lots of spill. ..." Simple Nature

I kind of thought cehowardGS said he was using torches with XML LED's, and that the Q5 was the housing. The pics in comment 50 don't show the torches to be very sharply focused, but maybe they are in real life conditions, possibly explaining why he's using two torches essentially side by side: to get a full road width of light.

comment #50 re; Q5 XML T6 torches for bike lights

"...When comparing 900 lumens in practice to say 450 lumens, most of you will barely notice the difference... but the runtime literally doubles. I ride with 200 lumens at night quite comfortably. ..." Simple Nature

Setting aside for the moment light loss variances in reflectors and lenses between different light models, wouldn't 900 lumens be twice the illumination of 450 lumens? Since I have some familiarity with f-stops associated with camera lens openings, I'm inclined to think of bike light illumination this way. On a camera lens, the difference between f4 and f5.6 is just 'one stop'. Seen in a photograph, the illumination difference between the two settings isn't that great, but f.5.6 requires twice the light to get the equivalent level of illumination of a photo shot at f4.

My Cygolite pace 150 is rated to have approximately 150 lumens on high setting ( for seeing the road, high-steady, I could use a little more). Using the photo lens analogy, that would suggest 900 lumens offers two and a half times the illumination that 150 lumens does? Sound about right? I think this is something consumers may benefit from understanding better.

Making things complicated, if I understand it correctly, achieving 900 lumens would require six times the power as does 150 lumens.

[Simple Nature]

You have those calculations about right. The human senses are not linear, rather they then to react in a logarithmic fashion (someone will probably correct me with the proper terminology regarding human physiology).

The Q5 reference for the flashlight bodies might well be their original intent. The "Q5" refers to the Cree XR-E Q5 LED. It is very common for people to use a low end flashlight to add a very bright LED like the XM-L. I've done as much to quite a few lights.

[wsbob]

From discussion on a thread titled: ' Suggestions for AA 3 or 3 cell NiMh 200+ Lumen over 18650 Li-ion? ', over at bikeforums 'Electronics, Lighting and Gadgets' category, I'm reposting a good explanation by bikeforums member 'Colleen c' of some of the mysteries and cautionary procedures associated with the use of 18650 lithium-ion batteries.

From post #3:

"18650 is like AA over dosing on steroid. It pack a lot more energy in a slightly larger package. This extra energy from 18650 allow for more ampacity deliver from the battery. Most 18650 can deliver 1.5 amp at 3.7 volt with ease. Better manufactor like the Panasonic cell easily handle over 2 amp load with less internal resistant than typical AA. That being said, the power from 18650 cell can allow flashlight manufactor to develope flashlight that is capable of producing 700+ lumens. Not only will you get more punch out of 18650 flashlight, but the battery is also rechargeable for many cycle. You will easily find fox and deer at a distant with most high power 18650 flashlight.

The downside of 18650 cell is that it is not for everyone. The disadvantage is that 18650 cell cannot be mishandle like AA cell. You need to take some care and precaution with 18650 cell. For a starter, never charge these cell unattended at home. Do not abuse them like dropping them or crushing the cell. The battery can causes fire when these warning are ignore. These incident are few and rare but it does happen. Personally, I myself own many 18650 cell and charged them countless time without ever having one issue. Stick with buying quality cell like AW, Redilast, Callie and you will be fine. Many cheaper brand like *.fire is OK and most likely safe but does not perform as good.

If you do venture into the world of 18650, you will find many flashlight that are rated over 200 lumens. Most peform at least 500 OTF when using the XML led. Being a newbie to 18650, you should stick to single cell 18650 flashlight. Do as much research with double 18650 cell flashlight before going that route. Shiningbeam has many flashlight using 18650 cell that are very good. Many are under the $50 price range, but that does not include the battery and charger. They also offer AA flashlight if you decide to stick with that route.

It is hard to go back to the AA route once you step up to the 18650 flashlight path. The first thing you will say is "wow" this light is very bright when you turn on a light utilizing 18650 cell. For some of us, it becomes a flashlight hobby after crossing that 18650 path.......(I'm one of those who had that 18650 flashlight addiction)"


From post #6:

"When two cells are in series and one of the two cell have a different state of charge, one cell can overheat causing heat buildup or gas comming out of the vent hole on the positive side of the cell. Since those cell are in an enclosed container in the body of the flashlight, this may lead to high pressure build up inside the body of the flashlight leading to an explosion of the housing. This is rare but has happen to some member at Candle power forum. Note: this effect is not limited to just 2cell 18650, but it also occurs in 2 cell CR123 batteries.

It is important to periodically check the final charge voltage of the cell after fully charge. There can be a chance where one cell was charged to 4.2v while the second cell did not charge at all. If both of these unbalace state of charge cell were to be use together in a 2cell 18650 flashlight, unpleasant result may occur.

Know how well your charger are working and learn how to use a digital volt meter and you should be alright.

BTW one important note: when choosing 18650 cell, stay with the cell that are protected. These cell has a small PC board at the negative side of the battery to protect things like over charging, over discharge and shorts. Most cell are sold as protected cell."

For people that for one reason or another would rather not use a bike specific designed light, couple this information with some of the earlier suggestions to this bikeportland forums thread about flashlight choices. You could wind up with a light that offers greater illumination for the money, that lends itself to a greater range of use than do bike specific lights.

[AJ08]

I ran across a very comprehensive review on tail lights here- http://bicycles.blogoverflow.com/201...-light-review/

I do wish manufacturers and reviewers would pick a light measurement such as lumens and stick to it. With such a wide range of brightness, how bright is too bright? I understand the need to be visible but when I'm driving, I hate, hate, hate people with those Xenon headlights that blind anyone unfortunate enough to be going in the opposite direction from them at night. Any thoughts of if some of these tail lights cross the line and might be a bit too bright for those who are behind your bike?

[Psyfalcon]

I've got the hotshot. It is bright, and mine is actually pointed a bit down due to my mounting so its not pointing into anyones eyes. The 2W led is about my limit though for blinking lights (maybe a bit less, it is adjustable). Much more and it can be blinding or distracting.

So the brightest off the shelf tail light is pushing it a bit... luckily they're not at the point of some of the mega flashing front lights you can buy off the shelf.