Choosing Auxiliary Lights

As with everything, it's important to choose the type of auxiliary lights that best meet your riding needs. This is not a one-size-fits-all affair. Choose the wrong type and you are bound to be less than fully satisfied.

Following are three main beam patterns commonly available:

- Fog lamps / foul weather lamps
- Driving lights
- Pencil beam

Each specializes for a specific function and is most effective in that application.
In all cases, and for a given light bulb wattage, the total amount of light available is the same. What differs among the three types of lamps is how that light is distributed. Traditionally, this was done by the lens. Today, many high performance auxiliary lights use a clear lens and rely on a Free Form reflector to control the light output.

For example, you can have a lot of light focused in a relatively compact area by a fog lamp or, using a pencil beam, stretch that the light over a longer distance.

Fog Lamps / foul weather lamps Fog lamps are meant to supplement low beams. As opposed to putting out a conical beam of far-reaching light, they a provide a broad spread of light that includes a sharp horizontal cut-off. The total amount of light is concentrated to the front and sides. By providing an enhanced amount of light to the side, fog lamps can make a major difference in improving night vision when traversing sinuous terrain. They are much more effective at lighting up the side of the road than driving lights. pro: Much more effective than other types of lighting for fog, rain, snow, and varying terrain such as mountain passes and canyons. Can also effectively be used to increase conspicuity to oncoming traffic without blinding the way that driving lights or high beams can. con: The beam does not project far down the road. At highway speed and on mainly straight sections of interstate, they may not provide enough range. note: This diagram is for illustrative purposes only to show relative differences in output. It does not necessarily reflect actual range for each type of lamp. see: Improving vision when riding or driving in fog

Auxiliary driving lights

Auxiliary driving lights are meant to supplement your high beams. As such, they need to be turned off whenever you dip your high beams as they can create blinding glare to oncoming drivers. For the same reason, auxiliary driving lamps should not be used during the day in order to increase conspicuity. The light output is optimized to put out a focused beam that reaches down the road. They can be extremely effective at providing good illumination at highway speeds.

pro:
The best type of light for average riding/driving over mostly straight sections at highway speeds.

con:
Much less effective if riding in the dark over mountain passes or sinuous terrain. In these situations, the light output will be in all the wrong places. The beam will shine deep into the cow field ahead while you lean the motorcycle over into the dark curve to the right or left. The projected cone of light provides a limited amount of peripheral roadside illumination. Innefective in fog and heavy snow.


Pencil Beam

As with driving lights, pencil beam auxiliary lights are also meant to supplement your high beams. Pencil beams cast the narrowest and most far-reaching beam of light. They are useful for riding and driving at very high speed over flat and straight terrain.

pro:
Pencil beam lamps may be the best option when riding/driving on roads such as those found in Nevada that are straight for miles on end.

con:
Pencil beams are not very useful for regular interstate use where the long and narrow beam will blind oncoming traffic at the slightest bend in the road. In addition, the narrow beams are quite poor at illuminating the sides of the road.

For use on mountain passes or country roads, they are worse than useless. They will illuminate points far away that have nothing to do with your constantly changing direction. As the following example illustrates, the strong, narrow beam tends to have a negative effect on your night vision.

As you follow a straight section, the road will be well-illuminated by the pencil beams. But as you lean in to follow a curve in the road, the strong and narrow pencil beam shines straight ahead, off the road and onto the field. It provides almost no peripheral illumination. As your head turns in to look at the curve, it will be comparatively dark. This difference can leave you temporarily night-blind until your night vision adapts. Now imagine this scenario occurring over and over again.

Maximizing effectiveness

No matter what type of auxiliary light you choose, improper aiming will result in a large drop in performance. Whether your lamps be driving or fog, a little time spent for careful aiming will yield noticeable results.

Summary:

Auxiliary lamps come in various guises. Like tools, each is optimized for a particular function. Each has strengths and shortcomings.

Determining the type of riding/driving that you do the most of will allow you to choose the one that best meets your needs.