Beam standards such as StVZO and what they cover

A light standard is a written list of tests a light has to pass. It can cover brightness at a set distance, the shape of the beam, whether it may flash, and how the light is marked. Different countries use different lists, so a light that passes in one place may not suit another.

What Germany's StVZO asks for

StVZO is Germany's Road Traffic Licensing Regulations¹. Its K-mark is the one riders see most often on lights. TUV NORD, a testing body, describes it as a safety standard for headlights and taillights. Here's what it asks of front lights, per that page.

• A clear cut-off line. The lamp must possess a clear cut-off line¹.
• Steady light only. Headlights are only permitted to operate in steady-on mode, and flashing functions are strictly prohibited¹.
• A marking. Certified products must display a clearly laser-etched or printed K-mark wave symbol followed by the approval number on the housing¹.
• A battery warning. The device must include a low-battery warning or power indicator function¹.

The European Cyclists' Federation lists a brightness floor as part of the German rules: a minimum brightness of at least 10 lux at a distance of 10 meters². It also describes a beam that is dipped and flat². Lights with a K number have a dip on their beam, designed to limit the blinding of oncoming cyclists and drivers².

Other places, other lists

Germany isn't the template everywhere. A general reference says some jurisdictions require compliance with standards defined by third parties³. For flashing, rules disagree. In some jurisdictions such as Germany and the Netherlands, flashing red tail lights are illegal, in others, they are allowed³.

The UK is an example of a different approach. The same source says reflectors must conform to BS 6102/2 or an equivalent European standard³. A light with a steady mode is considered approved only if it conforms to BS 6102/3 or an equivalent³. Check the current wording on the government's own pages, since a wiki can lag behind a change in the law.

What a mark does and doesn't tell you

A mark tells you the light was made to a named test list. It doesn't tell you your local law accepts it. That depends on the country or state where you ride. The rules page points to the official sources.

It also doesn't tell you the light is right for your bike. Wired lights need to match the port, which the wiring page covers.

Questions to ask

• Which standard does the maker name, and is the mark printed on the light?
• Is the standard from my country, or from somewhere else?
• Does the light flash, and does my local law allow that?
• Does the maker publish a test figure, such as lux at a stated distance? The lumens and lux page explains these.
• Where is the official text? Use the government or standards body, not a shop page.

If a maker says a light "meets the standard" and won't say which, treat that as a gap in the information.