|Bike lights are essential for commuters (providing they don't want to be ran over) and trail riders that enjoy the extra thrill of riding at night. Each light has its own strength and weaknesses, and many different bulb and power sources are available at a large array of different costs.|
For the purposes of this site, we are making the following definitions:
Safety Lights- These are lights meant to increase the rider's visibility at night, but are not built to provide enough unaided light to guide the rider safely at night.
Trail Lights- These lights are meant to produce enough light to guide the rider safely at night unaided by any other light sources (street lights, car lights, moon, etc).
Safety lights for bikes are defined (for the purposes of this site) as lights not meant to provide critical, unaided vision for riders, but rather to help them be seen by other vehicles.
The purpose of most forward facing safety lights is not to provide enough light for you (the rider) to see conditions in front of you, but to be seen by cars. While these aren't as critical as rear facing lights (providing you are following traffic laws, and riding on the right side of the road) they give you an extra safety cushion when crossing intersections, riding at night, etc.
Although they have many issues, there still exist a couple clear bodied front lights on the market. The problem lies in the fact that even when the beam is focused forward, there is still light shining into the rider's eyes, making it hard to see at critical times at night. The light pictured below is one of the best formats, as it directs all its light forward.
If you want to put any kind of omni-directional lights or flashers on your bike, make sure they are placed outside your field of vision, so they don't blind you or otherwise distract you at night.
Rear Facing Lights
As a general rule of thumb, when it comes to rear facing lights, the brighter the better. Strobe lights seem to work a little better then solid lights, because they attract more attention.
Under the International Vienna Convention on Road Traffic (1968) of the United Nations, a bicycle is a vehicle. Article 44 of the Convention stipulates that: "Cycles without an engine in international traffic shall: (c) 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 offense to even sell a bicycle not fitted with legally compliant lighting system. However not all countries impose this requirement on their domestic cyclists.
Many jurisdictions require bicycles to be fitted with reflectors at point of sale. In the United States this is regulated by the Consumer Product Safety Commission. CPSC compliant reflectors (also commonly fitted in other markets) 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 mounted 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. Individual jurisdictions define specific legal requirements in terms of light output and the size of lamp and reflector lenses, compliance with specified standards, or simply stipulate a minimum distance from which any lighting device should be visible. In some jurisdictions, some safe and practical systems (usually involving LED
based flashers) are illegal because blinking lights are only allowed on emergency vehicles, but those rules are rarely enforced.
UK requires a light approved to BS 6102 Part 3: 1986, but allows additional non-standard lights. In practice this means that users of powerful rechargeable systems need to add an additional light to meet legal requirements. Recent changes mean that a flashing LED
may be used, but only if it has no steady mode. National cyclists' organizations such as LAB (US) or CTC (UK) are a source of lighting information.
For the purposes of this site, a trail light is defined as a light that is meant to provide unaided critical vision for the rider. While many people use them for commuting on roads, they are often overkill for that purpose.
High-intensity discharge (HID) lights are the brightest lights currently available for bikes. They are very efficient, and very bright, but expensive. They also tend to have high power consumption (although they use less power than halogens for higher output), giving them a relatively limited burn time. Otherwise they have the same advantages and disadvantages as rechargeable halogen systems and, like halogen systems, they are designed primarily for off-road use, having rotationally symmetrical beams which cast as much light up as down. An additional disadvantage compared with halogen or LED
lights is that the HID lamp does not tolerate repeated strikes, and in many cases does not relight immediately after shutting down. Likewise, should the battery level fall too low, the lamp will shut down rather than dimming. But the battery life being longer than halogens tends to outweigh these problems, as many riders simply switch the light on and leave it running throughout the ride.
Advantages of rechargeable HID systems
- Very high power output
- High luminous efficacy
- Lamp requires warm up before reaching full output power and/or luminous efficacy
Although purpose-built for trail lighting, if you are using a HID lighting system on the road, lights should be adjusted to avoid dazzling oncoming traffic because HID bike lights can often meet or exceed the light production of a normal car head light.
Cyclists who only occasionally ride at night may opt for an inexpensive LED
front light and rear LED
flasher. Red or yellow LEDs
suitable for use as rear lights have been available for many years. Recently, white LEDs
that satisfy the requirements for a front light have come on the market, and some jurisdictions have made or are considering making these legally acceptable. Most LEDs
have a higher luminous efficacy than halogen lights, but poorly designed driving electronics can negate the advantage.
are adequate for riding on well-lit streets, but do not generally project a very bright beam as it is difficult to collimate the output from multiple LEDs
into a single usable beam. This can be overcome by using a few very high-power LEDs
- each with their own optics.
systems often include an option to dim the LEDs. LEDs
are well-suited to dimming, as halving the brightness usually more than doubles the battery life. By contrast, halving the brightness of a halogen bulb only slightly increases battery life.
Advantages of LEDs
Long battery life in flashing mode
- High luminous efficacy
- Last nearly indefinitely if the light is well designed
- Can be dimmed, usually with a slight gain in efficiency
- Instantaneous turn on/off
- Limited light output, especially in steady mode for many models
- Illegal in some jurisdiction
Although these lights were primarily designed for off-road use, where they are almost universal, many commuters now choose to use high-power halogen front lights which operate from a NiMH, lead-acid, or Li-ion rechargeable battery pack.
The lights used by most halogen rechargeable systems are cheap, bright and fairly simple: they project a cone of light (wide and narrow beam options are available) which is good for off-road use but not ideal for road use as it can dazzle oncoming road users. This is why rechargeable halogen lights do not meet legal requirements in some jurisdictions.
Many systems use standard commercial prefocused optics, making a wide range of power and beam width combinations available. Most systems allow 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.
Advantages of rechargeable halogen systems
- High power output
- Readily available
- Reasonable battery capacity
- Very reliable
- Easily removed from the bicycle
- Lamps are cheap and widely available.
- Limited run-time between battery recharges
- Power cycling reduces lamp life
Power Source Nickel Cadmium Battery (NiCd)
Using nickel oxide hydroxide and metallic cadmium as electrodes, NiCd batteries have longer life cycles and hold electrical charge longer. However, their voltage potential difference are often less than that of Nickel-metal Hydride's.
Nickel-Metal Hydride Battery (NiMH)
First developed around 1980's, Nickel-Metal Hyrdide batteries have a hydrogen-absorbing alloy for the negative electrode instead of cadmium. Even though NiMH batteries have higher voltage outputs, the batteries discharge quicker and have limited service lives compared with NiCd.
The technology behind Lithium-ion battery has not yet fully reached maturity. However, the batteries are the type of choice in many consumer electronics and have one of the best energy-to-mass ratios, no memory effect, and a slow loss of charge when not in use. The popularity of the batteries spread wider as the technology keeps on improving at the same time.
Lead Acid Batteries
Lead acid batteries are the oldest rechargeable battery type, and are by far the heaviest. They make up for this fact by being very cheap and having a long lifespan. Typically, this is the battery type used on cheaper halogen lights.