I installed one yellow headlamp in my V-Strom (keeping the one white headlamp). It's a 2500 degree color temperature Nokya Hyper Yellow bulb I bought online
here. (And yes, they are marked "DOT".)
I think it does help me be seen simply because it looks unusual. I do get far fewer people pulling stupid stuff right in front of me, but that could also be because the V-Strom has two headlights and is visually bigger from the front than my other two bikes.
As far as helping me to see, I think it's helpful, even on clear nights. After a bit of adaptation, my brain's visual centers seemed to learn how to make better use of the yellow light. For example, reflective surfaces really light up brighter with the yellow.
This next bit is a little hard to explain, but I think I have a better mental "picture" of what's out there with the one yellow lamp. Sort of like my brain knows that anything with a yellow tint was lit up by my headlights and not some other light, so I have a slightly more accurate 3-D map of things.
All that said, I would NOT want only a single yellow headlight -- it's useful in addition to a good white headlight, but by itself would be too dim for real nighttime use. If you have a single headlight, there are "gold" or yellow-tinted headlights that have an element of yellow but do not have the strong yellow color of the Nokya bulb I'm using. Phillips and Napa sell pretty good bulbs like this.
I perused the Indiana and DOT codes pretty closely, and basically there are two things I see that seem to make yellow headlights legally OK, or at least potentially defensible:
1) Motorcycles are required to have one white headlight, but nothing is said about more than one headlight, and there's no requirement that headlights have to be the same color. Red, green, and blue lights are forbidden on the front, and amber is of course OK (running lights and signals). Yellow is simply not mentioned either way, at least in Indiana.
2) What exactly constitutes the color "white" for a headlamp is not defined anywhere. At least in Indiana code, there's no scientific definition of a color temperature range that's acceptable. This may or may not fly if you encounter an especially obstinate cop.
In other words, it's pretty clear that a yellow headlight along with a white headlight is legal. And it's never been a problem for me riding in several states.
It's less clear whether a single yellow headlight would cause trouble. All it would take is for one judge or cop to say "I know the color white when I see it, and that ain't it -- change it".
You can sort of see the yellow in the left headlight here... sorry, don't have a good photo handy with the lights on.
thanks for the help!
