Has anyone used a flashlight as a taillight? How did you mount it?
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Has anyone used a flashlight as a taillight? How did you mount it?
I have a variety of Solarforce lights that accept P60 LED modules. (For those unfamiliar, the Solarforce (and others) are a knock-off of the Surefire 6P.) These lights are very modular and lego-able.
It would take about 10 seconds to install a drop-in module that uses a RED CREE X-PE2, driven at 1.7A, that makes 400-450 lumens (about 6W).
This would be brighter than any taillight I've seen for sale on the market, and it would cost about $30 (I already have the host flashlight and batteries).
The issue I'm dealing with at the moment, is how to mount it?
The bike I'm using doesn't have racks or panniers. I tried using a twofish lockblock to strap it to the seatpost, but it is too thick and my thigh hits it with every pedal stroke. Mounting to the chainstay results in the heel of my foot hitting the light. It seems like the only way to attach it to this bike may be to mount it directly behind the seatpost, but I don't know of any off-the-shelf mount that can do that.
Has anyone ever used a flashlight as a taillight? How did you mount it?
Thanks
It would take about 10 seconds to install a drop-in module that uses a RED CREE X-PE2, driven at 1.7A, that makes 400-450 lumens (about 6W).
This would be brighter than any taillight I've seen for sale on the market, and it would cost about $30 (I already have the host flashlight and batteries).
The issue I'm dealing with at the moment, is how to mount it?
The bike I'm using doesn't have racks or panniers. I tried using a twofish lockblock to strap it to the seatpost, but it is too thick and my thigh hits it with every pedal stroke. Mounting to the chainstay results in the heel of my foot hitting the light. It seems like the only way to attach it to this bike may be to mount it directly behind the seatpost, but I don't know of any off-the-shelf mount that can do that.
Has anyone ever used a flashlight as a taillight? How did you mount it?
Thanks
#2
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Some here: Ultrafire WF-501B Flashlight w/diffuser lens and some here: How would you mount a flashlight to the rear?
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I like to mount taillights on the saddle rails.
A plastic pipe that I have drilled a couple of holes in, some zip ties and anti-slip tape:
Ultrafire WF-501B with Luxeon K2 emitter and a $2 torch mount from eBay:
And there you have it, behind the seatpost and tucked neatly under the saddle
A plastic pipe that I have drilled a couple of holes in, some zip ties and anti-slip tape:
Ultrafire WF-501B with Luxeon K2 emitter and a $2 torch mount from eBay:
And there you have it, behind the seatpost and tucked neatly under the saddle
Last edited by ragnar.jensen; 09-17-13 at 02:54 PM. Reason: syntax is not the same thing as semantics
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True, there is not a lot of side visibility. The reflector is quite deep, resulting in a narrow beam.
I only use the Ultrafire as a backup, I usually mount a Dinotte 140 or a Magicshine...
...or an Akslen TL-60S there.
The Akslen in particular is very visible from the sides.
I only use the Ultrafire as a backup, I usually mount a Dinotte 140 or a Magicshine...
...or an Akslen TL-60S there.
The Akslen in particular is very visible from the sides.
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Thanks all for the replies.
The "hair roller" mount looks like an excellent idea - but I use an under seat bag so it probably won't work for me. :-(
I'm looking at an accessory mount, or some custom DIY pillow block, I'll let you know if I find something that works well.
Further comments are welcome if anyone has any more input. Thanks
The "hair roller" mount looks like an excellent idea - but I use an under seat bag so it probably won't work for me. :-(
I'm looking at an accessory mount, or some custom DIY pillow block, I'll let you know if I find something that works well.
Further comments are welcome if anyone has any more input. Thanks
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That mount that is shown in the second picture of the third post is very similar to what I have. It was for my primary front light, but I've been wanting to get one of those high powered red flashlights.... anyway, just to figure out how to mount a flashlight before ordering the red one, I started experimenting. I got that mount on the seat post- the light is not pointed straight back, but with a ~200 lumen light, I'm not sure you want that pointing straight into the drivers behind you anyway.
I only notice the body of the light rubbing against me if I'm coasting with my left leg/crank in the down position and bringing my thigh against the top tube. When I pedaling, I don't feel it rubbing against me- and I was wearing some rather baggy cargo shorts for that brief test run.*
*This was done during the daylight, with the light off, so I was in no danger of breaking any laws.
I only notice the body of the light rubbing against me if I'm coasting with my left leg/crank in the down position and bringing my thigh against the top tube. When I pedaling, I don't feel it rubbing against me- and I was wearing some rather baggy cargo shorts for that brief test run.*
*This was done during the daylight, with the light off, so I was in no danger of breaking any laws.
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Thanks all for the replies.
The "hair roller" mount looks like an excellent idea - but I use an under seat bag so it probably won't work for me. :-(
I'm looking at an accessory mount, or some custom DIY pillow block, I'll let you know if I find something that works well.
Further comments are welcome if anyone has any more input. Thanks
The "hair roller" mount looks like an excellent idea - but I use an under seat bag so it probably won't work for me. :-(
I'm looking at an accessory mount, or some custom DIY pillow block, I'll let you know if I find something that works well.
Further comments are welcome if anyone has any more input. Thanks
#11
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The end of the torch comes out very near my leg. Usually my leg will not hit it and I like that I can easily turn it off/on while on the fly.
I already own a very bright rear set-up ( Xeccon Geinea 1 rear ) that uses a red Cree XP-E emitter. The reason I wanted to mount the torch is so I could use something for "Daytime visibility"without draining the battery on the Geinea. Currently I am using one of the Nailbender ( Customlites ) drop-ins. My choice for Daytime was Amber coupled with their unique multi-flash-menu driver. As someone mentioned it is very narrow but for *my purpose ( *getting drivers attention at distance in the daytime ) I think it works pretty good for the money spent. I could wish for more output but then you start talking about multi-emitter set-ups ( like the DiNottte lamps ) and larger batteries which of course means lugging around more bulk and spending WAY more money.
Eventually I will replace the two-cell battery on the Geinea with a larger capacity two cell or just link the rear light to a larger battery to power both front and rear. Doing this will allow me to use the Geinea during the day more without worrying about losing run time for night use. At least with the Geinea you have the remote switch which allows you to operate the lamp ( on the fly ) only when you think you need it.
#13
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It would take about 10 seconds to install a drop-in module that uses a RED CREE X-PE2, driven at 1.7A, that makes 400-450 lumens (about 6W).
This would be brighter than any taillight I've seen for sale on the market, and it would cost about $30 (I already have the host flashlight and batteries).
#14
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I've used a flashlight as a taillight, but only for testing.
Just used strips from an old inner tube to attach the light to my seatpost.
https://www.youtube.com/watch?v=RFxCXb7Ju38
And, I also own a Solarforce L2 with a SF red drop-in:
https://www.youtube.com/watch?v=7qVXRuTyGBk
Just used strips from an old inner tube to attach the light to my seatpost.
https://www.youtube.com/watch?v=RFxCXb7Ju38
And, I also own a Solarforce L2 with a SF red drop-in:
https://www.youtube.com/watch?v=7qVXRuTyGBk
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Not sure about a 400+ lumen output with just one XP-E2. Normal driving current for these is listed around 700ma. Yes you can over drive the emitter but that is only going to give you so much. Don't believe output curves are going to be infinitely linear. At some point the curve will taper off as the emitter reaches it's heat limit. You might be able to run at 1.5A and that might get you something like 230-240 lumen...hard to say for sure. Surly you can also expect the output to drop significantly once the emitter begins to over heat ( which it will do when over driven )
https://www.cree.com/LED-Components-a...nal/XLamp-XPE2
You can see that lumens x amps is very linear. The reduction in output comes when junction temp (Tj) rises. The forced convection of using a light on a bike is significant - when I use my XML2 driven at 3.5 amps in a solar force host, the light does not even get warm to the touch. According to the data sheets, at Tj=25c, output =100%, and at Tj=50c, output =87%. As I mentioned, I expect the light to be completely cool to the touch while riding, so Tj<50c doesn't seem unreasonable, so therefore 390 emitter lumens doesn't seem unreasonable to expect. Yes, OTF lumens will be less - but then again, I've never seen bike light manufacturers advertise OTF lumen, much less ANSI lumens, so I feel my 390lm estimate is fairly apples-to-apples.
#16
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The current highest binning for XP-E2 is Q3, which is 93.9 lum/350mA. The driver I'm using is 1.7amp, which straight math says is 450 lumens at the emitter. If you look at the data sheets -
https://www.cree.com/LED-Components-a...nal/XLamp-XPE2
You can see that lumens x amps is very linear. The reduction in output comes when junction temp (Tj) rises. The forced convection of using a light on a bike is significant - when I use my XML2 driven at 3.5 amps in a solar force host, the light does not even get warm to the touch. According to the data sheets, at Tj=25c, output =100%, and at Tj=50c, output =87%. As I mentioned, I expect the light to be completely cool to the touch while riding, so Tj<50c doesn't seem unreasonable, so therefore 390 emitter lumens doesn't seem unreasonable to expect. Yes, OTF lumens will be less - but then again, I've never seen bike light manufacturers advertise OTF lumen, much less ANSI lumens, so I feel my 390lm estimate is fairly apples-to-apples.
https://www.cree.com/LED-Components-a...nal/XLamp-XPE2
You can see that lumens x amps is very linear. The reduction in output comes when junction temp (Tj) rises. The forced convection of using a light on a bike is significant - when I use my XML2 driven at 3.5 amps in a solar force host, the light does not even get warm to the touch. According to the data sheets, at Tj=25c, output =100%, and at Tj=50c, output =87%. As I mentioned, I expect the light to be completely cool to the touch while riding, so Tj<50c doesn't seem unreasonable, so therefore 390 emitter lumens doesn't seem unreasonable to expect. Yes, OTF lumens will be less - but then again, I've never seen bike light manufacturers advertise OTF lumen, much less ANSI lumens, so I feel my 390lm estimate is fairly apples-to-apples.
I routinely measure the heat output from the various bike lamps that I own. Not unusual to measure temperatures on the outside @ 50°C. ( After 10 min. ) and that with a fan blowing on it. I doubt any of those lamps are over-driving the emitters. I think it safe to say that the temperature at the emitter junction is going to be hotter than what is measured on the outside. By how much I can't say. Fifty degrees C. is definitely warm to the touch.
The more current you put through an emitter the faster it will get hot and the hotter it will get thus lowering the output. You can over-drive an emitter in an attempt to get more output but you still have thermal issues that are going to dampen the results. If you have good heat sinking it is going to help but rarely do manufacturers design a lamp with optimal thermal sinking properties.
I've never seen anyone use a 3.5amp driver for a single XM-L or L2 that was intended for bike use. Yeah, I suppose it could be done but it would certainly get damn hot ( real fast ). The L2's can handle heat better but if the lamp runs for a long time I'm certain there would still be an amount of heat related lumen loss. Anything beyond 15% loss is going to be quite noticeable ( not to mention the decrease in run time ) A lot depends of course on the heat sink and how well it can remove heat. Still, everything has limitations and anything that relies on ambient cooling definitely has limitations.
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The current highest binning for XP-E2 is Q3, which is 93.9 lum/350mA. The driver I'm using is 1.7amp, which straight math says is 450 lumens at the emitter. If you look at the data sheets -
https://www.cree.com/LED-Components-a...nal/XLamp-XPE2
You can see that lumens x amps is very linear. The reduction in output comes when junction temp (Tj) rises. The forced convection of using a light on a bike is significant - when I use my XML2 driven at 3.5 amps in a solar force host, the light does not even get warm to the touch. According to the data sheets, at Tj=25c, output =100%, and at Tj=50c, output =87%. As I mentioned, I expect the light to be completely cool to the touch while riding, so Tj<50c doesn't seem unreasonable, so therefore 390 emitter lumens doesn't seem unreasonable to expect. Yes, OTF lumens will be less - but then again, I've never seen bike light manufacturers advertise OTF lumen, much less ANSI lumens, so I feel my 390lm estimate is fairly apples-to-apples.
https://www.cree.com/LED-Components-a...nal/XLamp-XPE2
You can see that lumens x amps is very linear. The reduction in output comes when junction temp (Tj) rises. The forced convection of using a light on a bike is significant - when I use my XML2 driven at 3.5 amps in a solar force host, the light does not even get warm to the touch. According to the data sheets, at Tj=25c, output =100%, and at Tj=50c, output =87%. As I mentioned, I expect the light to be completely cool to the touch while riding, so Tj<50c doesn't seem unreasonable, so therefore 390 emitter lumens doesn't seem unreasonable to expect. Yes, OTF lumens will be less - but then again, I've never seen bike light manufacturers advertise OTF lumen, much less ANSI lumens, so I feel my 390lm estimate is fairly apples-to-apples.
If you made it yourself, it's unlikely the host has the heatsinking ability to withstand the thermal transfer.
If you bought the solarforce drop in with the cree red (I have the dx/fasttech versions), that's barely a 100 lumens (which is still really really killer bright for a taillight, more than plenty).
Your 390 lumen estimate is wrong.
I've never seen anyone use a 3.5amp driver for a single XM-L or L2 that was intended for bike use. Yeah, I suppose it could be done but it would certainly get damn hot ( real fast ). The L2's can handle heat better but if the lamp runs for a long time I'm certain there would still be an amount of heat related lumen loss. Anything beyond 15% loss is going to be quite noticeable ( not to mention the decrease in run time ) A lot depends of course on the heat sink and how well it can remove heat. Still, everything has limitations and anything that relies on ambient cooling definitely has limitations.
#18
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No way you're getting 400 lumens out of that xp-e2 red. The lumen per watt isn't a straight line curve, it tapers off, the peak efficiency is the highest between 1 watt and 2 watt per led for the cree xp/xr series. Plus the xp-e series were miniture version of xr-e and were never meant to be driven past 1a.
If you made it yourself, it's unlikely the host has the heatsinking ability to withstand the thermal transfer.
If you bought the solarforce drop in with the cree red (I have the dx/fasttech versions), that's barely a 100 lumens (which is still really really killer bright for a taillight, more than plenty).
Your 390 lumen estimate is wrong.
If you made it yourself, it's unlikely the host has the heatsinking ability to withstand the thermal transfer.
If you bought the solarforce drop in with the cree red (I have the dx/fasttech versions), that's barely a 100 lumens (which is still really really killer bright for a taillight, more than plenty).
Your 390 lumen estimate is wrong.
#19
Low duty cycle keeps average power low. e.g. a 3W light is on only 0.2 seconds every second so duty is 20% and avg power is 0.6W. This only works/helps if the on duration significantly shorter than the time it takes the system to reach thermal equilibrium when on constantly.
#20
#21
I like the look of your mount position, but in this instance it looks like the first good bump is going to knock the light out of that mount. Do you ride any rough trails with this set-up, and has the light fallen out?
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Yes, I have ridden the rough stuff with it. But a bit to my surprise, I have never had it shift position at all.
#23
I suspect the anti-slip tape helps a lot, but that cheapy mount did not give me confidence. That said I have dumped the exact same light onto the trail a few times during my initial attempts to mount it securely, so another bump is not going to make much difference.
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Hmm, I have even carried an Ultrafire WF-900L - which is almost three times heavier than the 501B - on the handlebar in the very same mount. No issues at all.
#25
Hmm, I have even carried an Ultrafire WF-900L - which is almost three times heavier than the 501B - on the handlebar in the very same mount. No issues at all.