softy wrote:I seriously had to read this post twice.....kenwstr wrote:Well I don't think the answer is more lumens. I have noticed while fishing at night, I can often navigate around the dams with no lights on. Ambient moonlight, starlight or that reflected from cloud is usually (except for complete darkness) sufficient to recognize all the terrain and obstacles around me and see the water edge. It is surprising how little light is actually needed once you are accustomed to it but with a light I am completely blind to everything outside the torch beam. There is a similar effect on the bike. My current light has a focusing ability so I can set it anywhere between a wide angle or a pencil thin spot. On the spot setting, I can usually see the path and road edges outside the beam from residual ambient light as the intensity of the spot beam at distance is not overwhelming but sufficient for adequate visibility though not wide enough. On the wide angle setting, the intensity of light returned from the road immediately in front of the bike blinds me to everything I need to see at distance even though the output intensity is even across the whole beam. The light is however bright enough to be a problem for other road users. So I think the issue here is light dispersion rather than intensity. What is needed is to focus most of the light out to a wide flat beam at distance while gradually reducing the amount of light put down to the road nearer the bike. The aim is to have an even intensity of light returned from the road surface to the rider regardless of distance within a reasonable range. This is not the same as an even intensity returned from say a wall. But one of the most crucial points is stray light, that is light dispersed above the horizontal plane of the light source. This is wasted light of little use to the cyclist and extremely annoying to other road users. Light dispersion needs to be controlled so that stray light is only sufficient for visibility to other road users and no more than this. Intense stray light blinds us in fog and targets motorists attention causing them to veer toward us which is a documented prominent factor in some cycling accidents.
Regards,
Ken
What has fishing got to do with cycling? Ken, can you please open my mind here.
As far as I'm aware you are required to have a light capable of being seen from 200metres (this is a minimum requirement) after a storm or during a windy stormy night you need to see debris such as branches twigs floods etc. Please don't tell me a fishing flashlight is apropiate. Travelling between 20 and 30 klicks with wet brake surfaces, lower lumen lights just don't cut it.
Also you want to be able to be seen in traffic at night. If your lights are significantly lower than motor vehicles you disappear into the background of all the vehicles lights.
As cyclists we need to deal with headlights of cars, as long as our headlights are not brighter, what is the difference?
The fishing analogy is just a way to explain the roll that light intensity contrast has to play in what you can and can't see. In very low light conditions, I can see quite well provided that light is distributed fairly evenly. I can for example locate my position in the terrain and navigate by that however, turn on a torch and I'm blind to everything outside that beam and therefore loose my position because I can't see enough of what's around me. The point is you don't actually need a whole lot of light to see where your are and what's going on around you but strong contrast will mess this up.
A similar thing happens while cycling because light intensity immediately in front of the bike is so great, my irises closes down to the extent I can no longer see to a sufficient distance ahead. This is not a question of lumens, it is a question of how the lumens you have are focused and dispersed at varying distances from the bike. You don't need a lot of lumens to be seen from 200m but if you go too bright, drivers will become targeted on your light. I for one wish to avoid being killed this way. The problem is most bike lights are designed as a torch, not as vehicular head lights; there is a fundamental difference in the light dispersion pattern. Stray light is a big issue for other road users and in fog. Badly designed lights waste 50% of the light as stray light going up into the air, this will just light up fog so it's impossible to see properly ahead. Well designed lights put all the light down on the road and do not light up as much fog so it's easier to see through it. If that was done, you would't need thousands of lumens. It would be far better if the manufacturers designed bicycle lights properly. Focusing the light into a broad flat beam, greatly increasing intensity toward the top cut off line of the beam. This would return light more evenly at all distances maintaining better visibility through the entire range with less energy output. The advantages of doing so include better visibility, less danger from targeting, longer battery life, fewer high beaming incidents. Regarding light dispersion, there are a few better designed lights around but very few that I have found.
There are sites on the web discussing attention targeting, it's a real thing where bright lights on bicycles have resulted in fatalities Google it if your interested.
Ken
