Bicycle lighting
Bicycle lighting is illumination attached to bicycles whose purpose above all is, along with reflectors, to improve the visibility of the bicycle and its rider to other road users under circumstances of poor ambient illumination. A secondary purpose is to illuminate reflective materials such as cat's eyes and traffic signs. A third purpose may be to illuminate the roadway so that the rider can see the way ahead. Serving the latter purposes require much more luminous flux and thus more power.
Many jurisdictions require one or more bicycle lights to be fitted to bicycles ridden at night — generally a white light in the front and a red light at the back, like with other vehicles.
History
Fire
The earliest bicycle lamps were oil-fueled and started to be manufactured in 1876 for the Ordinary and solid-tired tricycles. From 1896, acetylene gas lighting for bicycles started to be introduced and later in 1899, acetylene gas lamps for the motor-car became popular. Their carbide lamps were powered by acetylene gas, produced by combining calcium carbide with water. The light given was very bright, often called artificial daylight but the lamps required regular maintenance.Electricity
From as early as 1888, electric-powered bicycle lamps were manufactured but did not become a viable proposition until 1898. They comprised an incandescent bulb and either a lead-acid battery or a dynamo. Lead-acid batteries were replaced by dry cells and later by alkaline batteries. Dynamos improved in efficiency and reliability, recently being incorporated into the wheel hub, for example. Moulding techniques for plastics also improved, allowing lens optics to be improved and cost reduced. Incandescent bulbs were replaced first by halogen lamps and later by light-emitting diodes.Halogen lights
Although these lights were originally designed for off-road use, where they were almost universal, rechargeable halogen lights became popular with commuter cyclists.The lights used by most halogen rechargeable systems were cheap and bright, but fairly simple: they projected a cone of light which is good for off-road use but not ideal for road use as it can dazzle oncoming road users. This is why halogen lights do not meet legal requirements in some jurisdictions.
Many systems used standard commercial prefocused optics, making a wide range of power and beam width combinations available. Most systems allowed simultaneous connection of different lamps - for example, a wide and a narrow beam for off-road riding, or a high- and a low-power beam for road riding.
HID lights
lights were a brighter/more efficient alternative to filament bulbs prior to the widespread adoption of LEDs. Like halogen systems, they were designed primarily for off-road use, having rotationally symmetrical beams which cast as much light up as down. HID lamps were susceptible to damage from repeated strikes, and in many cases did not relight immediately after shutting down. Likewise, should the battery level fall too low, the lamp would shut down rather than dimming. But the longer battery life than halogens tends to negate these problems, as many riders would simply switch the light on and leave it running throughout the ride.Xenon strobes
Xenon strobes were an innovation in bicycle lighting; previously common in industrial applications. They were brighter than LEDs and sometimes used as rear lights.Lighting system
Electrical system
, either rechargeable or disposable, are often used to power electric bicycle lights. Where batteries are unwanted a magneto is used. In cycling circles the device is called a dynamo even though the device does not have a commutator. See section Dynamo systems for details.Voltages
3 volt:Often supplied by 2 AA or C/D cell batteries.
6 volt:
Sometimes 4 AA batteries or lead-acid batteries are used; also supplied from a bottle- or hub dynamo.
9 volt:
Sometimes supplied by a PP3 battery
12 volt:
Mostly supplied by sealed lead-acid batteries. The main advantage with this voltage is versatility of the electric system, such as the ability to charge a cell phone battery, though 5 volt USB is also used for that purpose too. It also allows electric air compressors to inflate tires. Some 12-volt dynamos are available too, though their watt rating is underpowered for medium to high watt applications.
Light sources
Virtually all bicycle lights on the market today, from the cheapest to the most expensive, are based on LEDs.Legal requirements
Under the International Vienna Convention on Road Traffic of the United Nations, a bicycle is a vehicle. Article 44 of the Convention stipulates that: "Cycles without an engine in international traffic shall: Be equipped with a red reflecting device at the rear and with devices such that the cycle can show a white or selective-yellow light to the front and a red light to the rear." In some countries, for example France, it may be an offence even to sell a bicycle not fitted with legally compliant lighting system. However, not all countries impose this requirement on cyclists.Many jurisdictions require bicycles to be fitted with reflectors at the point of sale. In the United States this is regulated by the Consumer Product Safety Commission. CPSC compliant reflectors have three retro-reflective panels positioned at 30° angles. The standard requires a forward-facing white reflector on the front of the bicycle, sideways-facing white reflectors on each wheel, a red reflector mounted on the rear, and yellow reflectors installed on the front and back of each pedal. Some interpret this as an endorsement of reflector-only night cycling.
Many jurisdictions require the use of a headlight and a rear light or reflector after dark. Most European countries and some US states require front and rear lights at night, while others allow reflectors only at the rear. Some jurisdictions impose requirements on light output and the size of lamp and reflector lenses; some require compliance with standards defined by third parties; some stipulate a minimum distance from which any lighting device should be visible. In some jurisdictions such as Germany and the Netherlands, flashing red tail lights are illegal, in others, they are allowed.
In the UK, the regulations governing bicycle lights are set out in the Road Vehicles Lighting Regulations 1989 and their subsequent amendments, summarized in the Highway Code. The regulations require a white front light, a red rear light, a red rear reflector,
and amber/yellow pedal reflectors on the front and rear of both pedals.
Reflectors must conform to BS 6102/2 or an equivalent European standard. The situation for lights is more complicated:
- a light with a steady mode is considered approved only if it conforms to BS 6102/3 or an equivalent European standard;
- a light without a steady mode is considered approved only if it flashes at a constant rate of between 60 and 240 flashes per minute and has a luminous intensity of at least 4 candela;
National cyclists' organisations such as LAB or CTC are a source of lighting information.
Safety
The use of lights for night riding is generally recommended or required by authorities as a basic safety precaution, even in a well-lit urban context. show a correlation between collisions and failure to use lights even during daytime.In countries where bicycles are used widely for commuting and short trips, such as the Netherlands and Scandinavia, bicycle head- and tail lighting regulation is strictly enforced by the authorities.
However, a study from 2013
shows that different lighting regulations seem to have little influence on bicycle accident rates, and points out a lack of studies into the safety benefits of bicycle lighting.
Front lighting
White LEDs are available with output ranging from a few lumens to high-powered units producing about as much light as an automotive headlamp, suitable for high speed use on unlit trails.LED systems often include an option to dim the LEDs, or to provide a flashing light.
Low-cost battery lights can be a good choice for occasional use, and usually meet legislative requirements. However, regular bicycle commuters would probably find it cost-effective to use rechargeable cells. Some headlamps use lithium-ion rechargeable battery packs, which may be recharged from a USB port.
Flashlights
Flashlights, although not specifically designed for bicycle use, are a viable alternative. They can be fastened to the bicycle handlebars with various mounting devices such as a lock-block. The round light pattern of a general purpose flashlight is inferior to the beam of a bicycle headlamp properly shaped to illuminate the roadway and not provide excess glare to oncoming traffic.Rear lighting
Most LED lights will work in either flashing or steady modes. Some LED lights have multiple banks of LEDs allowing both flashing and steady light at once. This can also be achieved by having one flashing light and one steady.In many countries, LED flashers are the norm for rear lights. In others such as Germany and the Netherlands flashing lights are forbidden by law. In the UK flashing LEDs are legal from October 2005, provided that the lights conform to the requirements of the current Road Vehicles Lighting regulations. Many vendors claim EU compliance, however, this provides no consistent safety or legal value across the Union.
The most common power source for rear LEDs is a set of alkaline cells and rechargeable cells. In both cases the battery tends to fail quickly when it goes; it is widely considered a good practice to have two rear lights in case a battery fails en route.
Low power lights are mainly for being seen, or as an emergency backup, and are the dominant choice for rear lights. Rear marker LED lamps may be operated on disposable coin-sized cells.
Some high-end rear lights incorporate turn signal and brake light functions, switched via a handlebar control via radio frequencies.