Originally Posted by steelbikeguy

I've had it happen on a quiet rural road.
It was after sunset, but not totally dark yet.
The oncoming bike had a very bright light aimed high enough to effectively blind me. It might matter that I was using my dynamo light, which is not nearly as bright as a lot of small battery lights.
It was very much like having a car's high beams shining into your eyes.

I recently bought a modest light from Light and Motion. Nice light, well made, but the beam appears to be designed for mountain biking.
When I've designed my own LED bike lights, I pick out optics to produce a beam that is around 7 degrees. This puts enough light far out in front of me without putting too much near me, which impacts my night vision.

This L&M light looks like it has a beam closer to 30 or 40 degrees. There's no reasonable way to aim it low enough to not put the main beam of the light into the eyes of someone coming towards you. I bought it on sale and out of curiosity. I really haven't used it more than a time or two. It makes a good back-up light, or a light for really deserted roads where no one else is around... or as a daytime "be seen" light. At night, with oncoming traffic, it would be so blinding to oncoming traffic that it would be a risk to me.

Unfortunately... I think a lot of folks buy these lights without any idea about what beam pattern is suitable, and only think that brighter is always better.

Steve in Peoria