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Old 11-11-09, 10:35 AM   #1
daven1986
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I need your help - light meter and blinkies

Hi all,

I am in correspondence with CTC in the UK with a suggestion of a campaign to improve cycle lighting. My argument is that many people buy the cheapest blinkies they can which have marketing such as "super bright" etc. but which are actually not very visible. So we are left with cyclists thinking they are visible to car drivers when in fact it is as though they haven't even got lights.

Now what I hope is that someone who has one of these cheap blinkies and access to a light meter could measure the light output. This is required to see if it is above or below the UK requirement of 4candelas (4 lumens). Now I suspect they are above 4 lumens but this is the first step to making us cyclists safer.

Thanks in advance

Daven
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Old 11-11-09, 11:46 AM   #2
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Accurate measurement of Lumens output of a device requires an integrating sphere and lab grade light meter per my understanding. Scarce and expensive equipment.

Also there is the problem that a light that meets minimum output requirements with new alkaline batteries will be a lot dimmer even with only half depleted ones or in cold weather. One reason I like dynamo lights.

The Eveready Lithium primary cells hold voltage level much better through their life and are much better in cold weather but are expensive.
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Old 11-11-09, 11:49 AM   #3
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Most LED Blinkies seem bright close up in the dark.
It is about which ones can be seen from the furthest distance that counts.
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Old 11-11-09, 12:09 PM   #4
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Ye I realise that it is a long shot however when I was in the car the other day, there were a huge number of cyclists who only had a blinky. This didn't help anyone see them at all. When I was a new cyclist I underestimated the light requirement, now I just want to get the message out there to other new cyclists in an effort to raise awareness.
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Old 11-11-09, 12:13 PM   #5
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The Smart SF and Planet Bike SF are very good for distance in the dark.
But one still needs to keep good batteries in them.
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Old 11-11-09, 12:17 PM   #6
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Ditto on the problems of measuring accurately. You also have to consider whether they have 3, 5, 7 or X elements and the color of the LED.

I have some 5 element amber blinkies as back up to the back up. They aren't extremely bright, but between the color, diffusion and blink pattern are quite noticeable. I know the type you are thinking of - the blue and white ones at DX are extremely small and weak. They are only good for parts for decent ones.

You might be better off trying to get photos of different ones at specified distances. Even then you'd have problems with different ambient light.
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Old 11-11-09, 12:17 PM   #7
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Most of the common ones I've seen in the LBS are pretty bright.
The problem is people run the same alkalines for a year.
And lumens are not the same as candela, probably 30x difference in this application.
http://en.wikipedia.org/wiki/Candela
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Old 11-11-09, 12:43 PM   #8
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Planet Bike and CatEye both used to make a fairly bright white front blinkie. The CatEye one was identical to their 3 or 5 (I forget) rear taillight except with a clear lens. But I could never find anyone who actually sold them and eventually come to favor amber in front.

FWIW, this place has a decent selection that is only a little overpriced. The 4 element AAA amber are quite bright (brighter than the 5 element ones I had) and I suspect the pure white one would be even brighter. A few items can be found on DX (== sku.5849) for much less.
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