Originally Posted by noglider

German law requires bike headlights to have a certain beam shape. There must be a sharp cutoff at the top of the beam to prevent blinding people. This is a good thing. It also mandates a maximum power, which I think is a bad thing. To make use of the lower power, the makers work hard to get the most out of the little power the lights emit. The specially shaped reflector puts most of the energy at the top of the beam. By aiming the light right, the light spreads as if it is shone from above, i.e. the close part of the field to the bike is not brighter than the far part. Definitely make sure the light isn't upside down, but I'm guessing it's not. Make sure it's aimed high enough. If your mechanics are used to lights made for the American market, they will point it down to prevent blinding people. A German spec light should be pointed straight ahead.

Try to ride close to a wall or some pillars and see where the top of the beam is on vertical surfaces. It should be right at the height of the light or maybe a tiny bit lower. This will ensure it doesn't go into anyone's eyes.

One nice thing about the German law is that these lights work well elsewhere. They don't have to have different designs for different markets. They mass produce these lights, and they're not terribly expensive.

Another annoying thing about the law is that it doesn't allow for flashing headlights or taillights. The authors claim flashing lights are too distractive. Clearly, many of us disagree.