Cycles of all sorts

Bicycle lighting has two purposes: seeing and being seen. There are many types of bicycle lights available, each with its own advantages and disadvantages. There is no one "best" solution for any rider, and many riders mix and match different technologies to provide the balance that works for them.

Batteries, either rechargeable or disposable, are often used to power electric bicycle lights. For bicycle touring, commuting or if managing your batteries is just too much of a nuisance, powering the lights with a electrical generator, or dynamo, may be a better option. Unlike batteries a dynamo lighting system has unlimited duration, but the maximum power output is relatively low (to some extent this is mitigated by good optics and slight overvolting of the lamp; a good dynamo nominally rated at 6 V is generally allowed to produce 7 V or so by its voltage limiting circuitry). In Germany it is illegal, for environmental reasons, to use lamps powered by disposable batteries except on the most lightweight cycles. This has stimulated the market for high quality dynamos such as B&M or Schmidt.

The least expensive bicycle headlights use an tungsten filament lamp. A more expensive, but brighter and more battery efficient alternative is the halogen lamp. The brightest type is the high power High Intensity Discharge (H.I.D) light, which requires special circuitry and a powerful battery. Some self-contained LED headlights are now a viable alternative to more conventional bicycle lights, although many are only suitable for either being seen or emergency use.

Lighting decisions may be driven by the power source (e.g. tourists choosing a dynamo system) or by the amount of light required (e.g. off-road riders choosing a H.I.D. rechargeable), but often it is a matter of personal preference or local availability. A low power headlight and a rear red LED are often sufficient for cycling at low speeds in familiar areas with sufficient ambient lighting. In more challenging conditions, upgrading to a more powerful headlight is recommended. The drawbacks of more powerful lighting may include some combination of greater weight, greater expense, and shorter run time.

A common setup for a bicycle commuter might include:

• a quartz-halogen headlight powered by a rechargeable battery pack or dynamo
• a LED tail light, either steady or flashing/pulsating
• a flashing/pulsating LED front light for conspicuousness

Before purchasing, installing, or using lights in a given area, verify that the lights will meet legal requirements. In some jurisdictions:

• the use of flashing/pulsating lights is prohibited
• lights may have to be certified to certain standards
• the colour of lights may be regulated (e.g. yellow vs. white LEDs for front position indicators)

Whether or not these factors affect the efficacy or utility of lights, your ability to collect compensation in the event of a collision can be reduced if the bicycle lighting did not comply with the letter of the law.

Safety

The use of lights for night riding is generally recommended as a basic safety precaution, but there appears to be no reputable published evidence that this (or most other conspicuity aids) has a measurable effect on safety. Most authorities hold to the view that lights are an important safety aid for night riding even in a well-lit urban context, and some studies show a correlation between collisions and failure to use lights.

It is generally believed that reflectors alone are inadequate for night riding (almost all cycling organisations unconditionally advocate using a headlight at night), but the Consumer Product Safety Commission and other regulatory agencies have declined to mandate the inclusion of active headlamps with new bicycles, citing increased costs compared to benefits and the fact that most bicycles are not ridden at night.

It has been estimated that 75% of bicycles used in the United States at night do not meet the legal requirements for lighting. This may be because the majority of unlit cyclists are riding in urban areas with many streetlights.