Light - How to adjust?

Adjusting the headlights

Step 1: Park the bicycle five meters in front of a wall in the dark. Mount the headlight on the handlebar or head tube and measure the height from the ground.

Step 2: Measure the same height on the wall and mark it with tape or chalk. Add a second mark at half the height.

Step 3: Switch on the spotlight and aim the brightest point at the lower mark. If no light falls over the upper mark, fix it. Otherwise, tilt the lamp a little further down.

Adjusting the rear light

The rear light is primarily for your own visibility - the risk of glare is low. Mount the light at a height of 25 centimetres to 1.20 meters and make sure that panniers or blowing coats do not cover it.

Legal background

DE: The Road Traffic Licensing Regulations (StVZO § 67, paragraph 3, sentence 2) says:
"The headlamp must be adjusted so that it does not dazzle other road users".
The legal text was adapted to modern LED lights in 2017.

CH: The Ordinance on the Technical Requirements for Road Vehicles (Art. 179a para. 1 VTS) for motorcycle lighting: 
"The lights must not dazzle and must be visible at 100 m at night in good weather conditions."

There is no precise definition of how this requirement is to be achieved in the law.