Originally Posted by
diff_lock2
My problem is not lumens, but beam patterns. For off road use a round beam is fine, but on the road i want a downward firing light with a rectangular beam shape and nice spill. Now i use mr16 lights, they are really wastefull on the road, but really light up the forest. Some dynamo lights have really good patterns but lack the power. Time to do some moding.
Beam pattern is very important. Light efficiency can be improved over 50% by using an elliptical beam pattern. All motor vehicle headlights incorporate elliptical beam patterns in their design for good reason. I did a DIY
1-watt Luxeon LED star in a matching Fraen elliptical lens and holder to replace the dynamo type headlight that came in the kit.
The light output is much higher and much improved by using the 10 X 20 degree elliptical pattern. Attaching the light at the front wheel axel improves the ability to see obstacles but a policeman stopped me and informed me that state law requires all headlights be a minimum of 2 feet above the pavement so I had to reinstall the light just below my handlebars. I am limited to LED lights that function at or below 500mA as I am using a dynamo system. Even with my small 45 lumen 1-watt LED I can see just fine with it. Granted, more is always better when it comes to light output but I needed an unlimited light runtime so I must live with a 500mA power limit.
