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  1. #1
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    Super Compact MTB Bike light - New Technology

    n October 2006, a company by the name of Cree - released for distribution - the 70 lumens per watt 7090 xlamp (http://www.cree.com/products/xlamp.asp). With this release, the LED has now surpassed even the Solarc HID (found in most HID Bike lights @ 45-60 lumens per Watt). By comparison, the Current Luxeon efficiency leader is the K2 (2nd generation luxeon III) at ~40 lumens per watt.

    “Whoop de do, What does it all mean Basil?”. Austin Powers

    For those of you who do not completely understand the unit of Luminous intensity (lumens), it is basically a measure of total light output, and does not discriminate for beam hot spot. The higher the Lumens/Watt = lower power consumption = Smaller battery = lower operating heat = longer run times.

    It is true that the HID is a brighter single light source, so you would have to use multiple LED’s to match the brightness. One downfall of the HID is that it has to be run above 10 watts, and therefore, this minimum power consumption dictates a large battery and a relatively high level setting at all times. In contrast, the LED is a solid state device and can easily be controlled to lower output levels – this saving battery life.

    Other benefits for the LED include: More pleasing color (true white instead of blue) and longer life (up to 50,000 hours versus a rating of 1000 hours for the HID), This is dependent of vibration and abuse (HID).

    I have recently obtained a Fenix P1D-CE for $69. This little light (no bigger that my thumb) uses the Cree Xlamp and is powered by a single CR123 lithium battery. Output on high is approximately 130 lumens with a continuous runtime of 2.5 hours (using non-rechargeable 3 volt CR123 (1300mah capacity). Since CR123 batteries are $1 each (best price), I use Rechargeable 3.7 volt RCR123’s. The Rechargeable cells are a lower capacity (usually 800mah capacity) and as such have a continuous runtime of 50 minutes.

    I would make the argument that this little light is the only thing that you will need for technical mountain biking. As I have been riding nearly every Wednesday on the National trail in Phoenix for 5 years. The only slight modification to this light would be to gain a better compromise between the current spot beam and flood – slightly moor flood and less spot would be favorable.

    By comparison, the Fenix P1D is significantly brighter that the L&M Vega, and Nightrider Minewt. And equivalent to the 5 Watt Dinotte.

    Mounting is accomplished via a Twofish lockblock to the handlebar.

    @$69 – you can afford to buy two, and have the equivalent output to a 260 lumen HID.

  2. #2
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    Quote Originally Posted by kopec
    Output on high is approximately 130 lumens with a continuous runtime of 2.5 hours (using non-rechargeable 3 volt CR123 (1300mah capacity).
    Actually the spec is for 1 hour runtime at 130lm, 2.5 hours is only at 70lm.

    @$69 – you can afford to buy two, and have the equivalent output to a 260 lumen HID.
    Except HIDs are about 650lm! Personally I'm happier with 3 Crees for mountain biking (though 4 top spec ones for a real HID busting 640lm, as with my next project would be nice) - see my new thread for details.

  3. #3
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    I would make the argument that this little light is the only thing that you will need for technical mountain biking.

    At 130 lumen? Technical mountain biking? At what? 5mph?

    130 lumen sucks for my "technical mountain biking". I want to go fast at night. I don't want to just ride at night.

    I ride night single-track with 1850 lumen.

    130 lumen? You don't see anything. Over 5mph, you are over-riding the light. At 30mph you are dead... you couldn't see the giant porcupine sitting in the trail. Have you ever rode into bright headlights with 130 lumen? I am not all that fond of shielding my eyes from on-coming car lights because my light is too weak to penetrate.

    I also don't believe the LED light is more "pleasing". I ride with LED lights as well. I'll take the HID anyday for "pleasing" effects. But then my single HID light has the lumen's of fifteen 130 lumen LED lights. That is probably what really pleases me. It also runs for 5.5 hours at full smack down. Gotta love that.

    I'm sure the little LED has it's place, but it is not in technical, night mountain biking at speed on ripping single-track.

  4. #4
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    How about a 5 buck 12v 10w halogen lamp overvolted to 14.4v? Thats 730 lumens @ about 60 lumens/watt.

  5. #5
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    Quote Originally Posted by 29Colossus
    I ride night single-track with 1850 lumen.
    What light's that then? I don't think even the original 20W Cateye Stadium pumped out that much.

    (sorry being picky tonight, I agree with your general drift, but reckon 350-400lm is enough for riding fast off-road at night - I've certainly done plenty with that).

  6. #6
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    Quote Originally Posted by Stregone
    How about a 5 buck 12v 10w halogen lamp overvolted to 14.4v? Thats 730 lumens @ about 60 lumens/watt.
    No way it is - more like 300lm and 22lm/W!

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    Quote Originally Posted by chrism
    What light's that then? I don't think even the original 20W Cateye Stadium pumped out that much.

    (sorry being picky tonight, I agree with your general drift, but reckon 350-400lm is enough for riding fast off-road at night - I've certainly done plenty with that).
    Trail Tech Eclipse 30w HID.

  8. #8
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    Quote Originally Posted by 29Colossus
    Trail Tech Eclipse 30w HID.
    Lumens sounds about right then. Rather more than most of us "need" for night riding though, and how much does your battery weigh to run that beast for 5.5 hours?

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    130 lumens

    Points taken,

    I suggested 2 x 130 lumen lights for technical riding. 130 lumens is do-able, but the sidespill is missing on this light. On moonlit nights this is not a problem, but very dark nights require extra illumination, or your balance and periferal vision is effected. If you have ever ridden National trail at night, you will know what I mean by Technical. 260 lumens is not going to turn night into day, but I value night riding as an alternative to the day. I need enough light to be safe, but too much light takes the fun out of it.

    Also, if you are arguing about which is better, 70 lumens per watt is getting close to twice the efficiency as the solarc.

    My main point was the efficiency and the incredible reduction in size that this brings.

  10. #10
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    Quote Originally Posted by 29Colossus
    130 lumen? You don't see anything. Over 5mph, you are over-riding the light. At 30mph you are dead... you couldn't see the giant porcupine sitting in the trail. Have you ever rode into bright headlights with 130 lumen? I am not all that fond of shielding my eyes from on-coming car lights because my light is too weak to penetrate.
    .
    I dont ride any trails where I have to watch our for cars. This is out in the open without any ambient light.

  11. #11
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    Quote Originally Posted by chrism
    No way it is - more like 300lm and 22lm/W!
    Thats about right for an MR11 bulb, but those tiny things suck. MR16 is what you want to use.

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    Quote Originally Posted by chrism
    Lumens sounds about right then. Rather more than most of us "need" for night riding though, and how much does your battery weigh to run that beast for 5.5 hours?
    1.9lbs in a water/fire proof case for the big one. I also have a 3.5 hour battery. It is a bit over 1lb. wrapped.

  13. #13
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    Sorry, but your MR16 is about the same efficiency as an MR11. The reflector design might be a little better, but there is no way you will get anywhere near the efficiency of an HID or Cree LED.

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    Quote Originally Posted by Stregone
    How about a 5 buck 12v 10w halogen lamp overvolted to 14.4v? Thats 730 lumens @ about 60 lumens/watt.
    Except overvolting also increases the current draw, in the case of a 20% overvolt you're increasing the actually current draw 44% and need to calculate that into your lumens/watt calculations. Its no longer drawing just 10W... its now drawing 14.4 watts. 730 / 14.4 = 50.7 lumens/watt. You're also DRASTICALLY shortening the bulb life though, to about 16% of normal average. If its a "2000 hour" bulb, expect around 320 hours instead. I use the overvolt trick myself (to a more radical extreme, 100% overvolting) on a couple lamps and know of what I speak.
    I don't post to generate business for myself or make like I'm better than sliced bread

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    Quote Originally Posted by DeeEight
    Except overvolting also increases the current draw, in the case of a 20% overvolt you're increasing the actually current draw 44% and need to calculate that into your lumens/watt calculations. Its no longer drawing just 10W... its now drawing 14.4 watts. 730 / 14.4 = 50.7 lumens/watt. You're also DRASTICALLY shortening the bulb life though, to about 16% of normal average. If its a "2000 hour" bulb, expect around 320 hours instead. I use the overvolt trick myself (to a more radical extreme, 100% overvolting) on a couple lamps and know of what I speak.
    According to this its 12.4 watts for 59 lumens per watt. And a hundred or two hours life on a bulb that costs 3-10 bucks isn't a problem really, when its doing about as well as something with an $80 bulb. A couple hundred hours is probably an entire winter riding season for most people.

    How did that 100% overvolting work out?

  16. #16
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    Quote Originally Posted by Stregone
    According to this its 12.4 watts for 59 lumens per watt. And a hundred or two hours life on a bulb that costs 3-10 bucks isn't a problem really, when its doing about as well as something with an $80 bulb. A couple hundred hours is probably an entire winter riding season for most people.

    How did that 100% overvolting work out?
    Not really convinced by the figures there. After all lumens is a measure of total light output across the whole beam, not how much you can focus in a small spot, and the only real advantage of a larger reflector is improving the focusing ability. The actual light bulbs inside the MR11 and MR16 are much the same. Empirically, I'd say my triple Cree, giving a nominal 400lumens (though less than that accounting for losses in the lens - don't think I'm losing much due to heating given my overkill h/s) is as good as a 10% overvolted MR11 20W, and also as good as a 10% overvolted 20W halogen in huge 90mm reflector (an orienteering headlamp). I'll also point out that I wasn't actually expecting it to be as good as the orienteering headlamp - thought I'd need to build a much more powerful LED light for that - I think the much more pure white light (which makes the halogen look very yellow) helps a lot.

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    you might mention LED's for all practical purposes never fail. That 1850 lumen beast sounds like fun. Hope you like riding alone! When I ride with my puny ~360 lumens of LED's on city trails a good percentage of crossing traffic curses me. (2 dinottes in center, a pair of brinkmann nylon 3w throwers attached permanent to the bar ends) whole thing is under 700g. I tell 'em **** you, get a respectable light. With a 30w hid I would be out of line.

    I'm looking at that homebrew cree, I like. I used to build car stereo stuff out of aluminum in my sleep, I better get off my ass and start a project. I think a sixer' out of that 1" x 1"
    square should do... better search the surplus places for some Li batteries. According (compared to, LOL!) Fox Fury that should be good for 120 mph, right? Maybe 8 then!

  18. #18
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    Quote Originally Posted by 29Colossus
    [i]
    At 130 lumen? Technical mountain biking? At what? 5mph?

    130 lumen sucks for my "technical mountain biking". I want to go fast at night. I don't want to just ride at night.

    I ride night single-track with 1850 lumen.

    130 lumen? You don't see anything. Over 5mph, you are over-riding the light. At 30mph you are dead... you couldn't see the giant porcupine sitting in the trail. Have you ever rode into bright headlights with 130 lumen? I am not all that fond of shielding my eyes from on-coming car lights because my light is too weak to penetrate.

    I also don't believe the LED light is more "pleasing". I ride with LED lights as well. I'll take the HID anyday for "pleasing" effects. But then my single HID light has the lumen's of fifteen 130 lumen LED lights. That is probably what really pleases me. It also runs for 5.5 hours at full smack down. Gotta love that.

    I'm sure the little LED has it's place, but it is not in technical, night mountain biking at speed on ripping single-track.
    How fast can you ride technical terrain anyway? If you're rippin' it ain't technical. 5 mph seems about a reasonable speed for technical terrain.

  19. #19
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    Quote Originally Posted by Stregone
    According to this its 12.4 watts for 59 lumens per watt. And a hundred or two hours life on a bulb that costs 3-10 bucks isn't a problem really, when its doing about as well as something with an $80 bulb. A couple hundred hours is probably an entire winter riding season for most people.

    How did that 100% overvolting work out?
    Unfortunetly that chart as far as watts goes flubbed the math, or seems to think you just add 20% to the amp rating of the bulb to determine how much current its now drawing. It also relies on a lot of rounding to 1 decimal place as far as amps go. Of course manufacturers fudge the watts ratings by rounding up themselves.

    Luminous Flux is the what lumens are, and the overvolting equations just happen to deal with luminous flux... that increases to the exponent of 3.5, the current draw squares itself, and the bulb life is exponential to -10. This is easier to work out if your calculator has a y to the x button. Y would be the voltage change (use 1.2 for a 20% overvolt, 1.1 for 10%, 2 for 100% etc) and X would be 3.5 for the lumens figure. so 20% overvolt bumps the lumens up 89%, so on.

    I took a 6v-10W bulb (rated for 1.6 amps so ok it was really 9.6W) and jammed it up to 12V with an SLA pack. The battery pack was rated for 2.2Ah. The jump in lumens is over 11 times its original figure. The current draw is unfortunetly now 6.4 Amp. Effective endurance of the battery? About 20 minutes before the light visibly yellowed. Actual perceived brightness? Car highbeams stuff. I just used it mostly as a high beam for super technical stuff and for messing with the riders with HID lights ahead of me. I mean, a guy riding with a 13W HID 10 feet in front of me had SHADOWS that his light couldn't overcome projecting past him.
    I don't post to generate business for myself or make like I'm better than sliced bread

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    Quote Originally Posted by MikeDee
    How fast can you ride technical terrain anyway? If you're rippin' it ain't technical. 5 mph seems about a reasonable speed for technical terrain.
    "rippin" is relative and can be achieved on ANY type of surface or terrain.


  21. #21
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    Quote Originally Posted by kopec
    I have recently obtained a Fenix P1D-CE for $69.

    @$69 – you can afford to buy two, and have the equivalent output to a 260 lumen HID.
    Where?

  22. #22
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    Kree and other LED flashlights

    Quote Originally Posted by kopec
    ...edited...I have recently obtained a Fenix P1D-CE for $69. This little light (no bigger that my thumb) uses the Cree Xlamp and is powered by a single CR123 lithium battery. Output on high is approximately 130 lumens with a continuous runtime of 2.5 hours (using non-rechargeable 3 volt CR123 (1300mah capacity). Since CR123 batteries are $1 each (best price), I use Rechargeable 3.7 volt RCR123’s. The Rechargeable cells are a lower capacity (usually 800mah capacity) and as such have a continuous runtime of 50 minutes.

    I would make the argument that this little light is the only thing that you will need for technical mountain biking. As I have been riding nearly every Wednesday on the National trail in Phoenix for 5 years. The only slight modification to this light would be to gain a better compromise between the current spot beam and flood – slightly moor flood and less spot would be favorable.
    By comparison, the Fenix P1D is significantly brighter that the L&M Vega, and Nightrider Minewt. And equivalent to the 5 Watt Dinotte.

    Mounting is accomplished via a Twofish lockblock to the handlebar.

    @$69 – you can afford to buy two, and have the equivalent output to a 260 lumen HID.
    1/16/07 Yep, that's the thing about LED (flashlights), the optics leave much to be desired. I have no doubt that the Fenix P1D you mentioned is a very bright light. After viewing some specs on the Fenix P1D it is quite clear that the small reflector means a very tight beam. We can agree that a wider beam would be more usable for MTB'n. You didn't mention how the Fenix operated. The Fenix seems to have five different levels of light output (including a sos function), me thinks that's a little much. Added to this is the fact that the levels are changed by twist-turning the flashlight.. I guess that's fine if you have it in your hands but mount that baby anywhere and your going to have fun turning it on/off and changing levels. I am amazed though that you got 50 min of runtime out of one 800mah rechargable Cr-123 Li-ion cell. Is that without any loss in brightness? I find that hard to believe.
    If someone wanted a very bright LED flashlight with a slightly wider beam I would like to recommend this one> http://www.qualitychinagoods.com/sup...ded-p-467.html . Yes, it is a cheaply made Chinese made LED flashlight, it cost about $30 with free shipping. I have bought two (different) LED flashlights from this web site. The 8watt Super bright has a very nice beam, very white and makes a great cheap helmet light. Running it with two 800mah Li-ion batteries (also sold cheaply on their site) it runs about 40-45 min. with good brightness. I would compare the beam to a 10watt spot halogen although the halogen has a slightly wider beam pattern. Anyway, the beam is wider than the smaller flashlights because of the wider reflector. I believe the LED they are using is the K-2 although I won't swear by it. The one (8w) I own has Lumileds written on the side of it. I also bought one of the 10watt Super bright LED lights. It was marketed as using the K-2. It is even brighter but with a more focused light. I opened it up and it did have lumileds written on the star mounted LED. Unfortunately for me I broke it trying to get it back together.. I wrote them back and they said to send it back. Two months later I got a replacement for free (not including my return airmail). Anyway, they are cheap lights but for $30, what the hey. Oh, when I compared the two LEDs (8w vs. 10w ) to me they looked the same. The LED on the 10watt does show some discoloring (some slight yellowing) but no so with the 8w. One last thing...forget all the 8, 10, 12..etc. watt nonsense on these Chinese lights, this is just marketing crap. (last note: my internet order took two weeks to ship and came airmail)

  23. #23
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    Quote Originally Posted by Cat-man-do
    If someone wanted a very bright LED flashlight with a slightly wider beam I would like to recommend this one> http://www.qualitychinagoods.com/sup...ded-p-467.html
    I've got that one, from 5th unit. It is the 18650 version though, very bright, and throws like nothing i've seen before (awaiting Lumapower M1 XR-E...). But a broad beam? No way! It's got a lot of sidespill, but certainly no wide beam, this is throw power to the max. I'm liking the new 5th unit by the way, selling 18650 1800mAh's for $3,50 shipped. That way you can build Li-ion packs for (way) less than a comparable NiMH pack.

  24. #24
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    For a bikelight, you will definitely want something that will fit 18650s for the extra burn time. You will kill a single cr123 in no time (only ~700mAh). I have the Lux III model of the Huntlight that fits the 18650 ($40). It's really amazingly bright with great throw (some spill but nowhere near as much as I would want for a bike light). With a Cree, this thing would be blazing. The Lumapower M1 with the Turbo head would probably make a great bike light, especially with a XR-E. You would most certainly want something with a larger reflector to get a wider beam pattern than most flashlights.

    Unless you have a really nice regulator with low drop out around 3V per Li-Ion cell than I would highly recommend going with protected cells. They cost more but having some protection against blowing up would be a good thing. Here's a good source for the protected 18650 (or r123) and charger:

    http://www.candlepowerforums.com/vb/...09&postcount=2

    You have to be careful when selecting a flashlight because the protected cells are slightly larger diameter than the unprotected. Some will not fit the protected cells.
    Long Live Long Rides

  25. #25
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    Quote Originally Posted by Homebrew
    For a bikelight, you will definitely want something that will fit 18650s for the extra burn time. You will kill a single cr123 in no time (only ~700mAh). I have the Lux III model of the Huntlight that fits the 18650 ($40). It's really amazingly bright with great throw (some spill but nowhere near as much as I would want for a bike light). With a Cree, this thing would be blazing. The Lumapower M1 with the Turbo head would probably make a great bike light, especially with a XR-E. You would most certainly want something with a larger reflector to get a wider beam pattern than most flashlights.

    Unless you have a really nice regulator with low drop out around 3V per Li-Ion cell than I would highly recommend going with protected cells. They cost more but having some protection against blowing up would be a good thing. Here's a good source for the protected 18650 (or r123) and charger:

    http://www.candlepowerforums.com/vb/...09&postcount=2

    You have to be careful when selecting a flashlight because the protected cells are slightly larger diameter than the unprotected. Some will not fit the protected cells.
    I've build a 'achesalot' (C) triple XR-E bikelight with a bFlex driver. I'm currently fabricating a holder for four 18650 cells (the 1800mA unprotected ones), wired in series with a protection PCB for the complete pack.
    The whole idea of using a flashlight on a bicycle is a bit beyond me, maybe nice for commuting and such, but serious offroading at night? Just to little light in a beam that isnt broad enough. I carry the 18650 LuxIII light as a backup on the shoulderstrap of my Camelbak. In flashlights I've never run the cells completely down, especially with the new Lumapower M1 that regulates for a few hours on a 18650. I never use my flashlights for such a period continiously, maybe if I'm out camping for a week or so. But than i'd have some spare cells with me. Plus the fact that I've never had any problems with Li-ions, even ran a RCR123 way below 3V, tossed it in the charger (outside, I've heard the stories). That cell is running fine as always, little bit less capacity. But then again, those 123's are empty in a flash anyway.
    Last edited by brum; 01-16-2007 at 08:11 AM.

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