Bicycle Light Comparison

November 2006: After ordering and receiving an HID Helmet Mount Light Kit from Trail Tech, I decided to try comparing it to the two other lights I've been using for around a year.

The Headlights

Light Output Comparison

To give an idea of the field of illumination and color of each headlight, I aimed them at a garage door from 20 feet away. The images were taken with an automatic digital camera, sans flash so there is some averaging of the illumination levels.

Observations

The HID Light wins hands down for sheer output. Its light is very white, not as blue as the images imply. The halogen light seems quite yellow here, although it's hard for me to notice until the batteries get low. The LED light wins for having the purest white.

The LED light seems weak, but it's strong enough to illuminate the road directly in front of a bicycle. Its light is highly focused. This Viewpoint Gen3 was quite inexpensive on clearance. Newer Luxeon Emitter lights are more powerful and come with as many as three headlights combined. Their long operating times and continued improvements means that they will be competition for HID lights soon.

Halogen lights have been the low cost choice for years. For offroad/trail use, however, a single 10W Halogen light is barely adequate. A helmet mounted light works best.

I have ridden many evenings using two 10W Halogens, one on the helmet and one on the handlebar. This combination is really useful since one shows what's in front of the bike while the other can be used to scan ahead.

In comparison, the HID light is a big step up. The light field is both larger and brighter than the Halogen's, easily over four times as much. There is also more scattered light than the pictures imply; part of the roof and driveway were reflecting some light. However, these lights are expensive. HID Bicycle Lights range from about $300 to $800 for bicycling specific models. Fortunately this light kit brings the entry point down to $200.

HID lights require more powerful batteries and therefore weigh more. The HID Helmet Light Kit that I bought is intended for motorcycle use, and is heavier still (but quite sturdy). The battery alone is 23 oz, almost 1.5 lbs. It's about halfway between the 6V battery pack for a Halogen light and a 6V SLA battery in terms of size and weight.

Also note: according to Trail Tech, the MR11 HID Light needs to travel at 5 to 10 mph for adequate cooling. If it overheats it will shut down. Since I only ride with lights in the Fall and Winter (after DST ends), I'm not expecting this to be a problem. Night riding with it on warm summer nights may not be possible.

Modified Helmet Mount

Mounting the Trail Tech light kit on a bicycle helmet poses a bit of challenge. The light unit has a curved base with a preinstalled patch of velcro-like hook fasteners. It comes with two more patches that stick on, and you're supposed to attach one to the helmet's curved surface so that they can be pressed together.

On a bicycle helmet, there's a good chance there won't be a smooth, flat surface in a good location for installing this patch. Another concern: a bike helmet's thin microshell surface may not provide enough support. It's not as strong as a fiberglass motorcycle helmet.

I decided to make my own mounting, so that I could attach this light using a velcro strap with a plastic buckle instead.

Modified bicycle helmet mount for Trail Tech headlight kit

The carrier for the light unit is made from a loop of aluminum bar stock, folded in a bench vise with a bit of hammer for added persuasion. I used a drill and two sheet metal screws to close it at the front.

The patch of hook fasteners for the light unit is installed on top. I placed a rectangle of foam weatherstripping tape on the bottom to eliminate rattle, and to hold it in place better.

The velcro strap with its attached buckle passes through the aluminum bar loop and two of the helmet's cooling vents to hold the light unit in place. I used a second strap to secure the cord to the back of the helmet. It's just visible on top in this picture.

There is one shortcoming to this setup in comparison to headlights made for bicycling. As you can see from this picture, the control for the Trail Tech light is at the end of the light unit's cable. This control has LEDs that indicate the remaining power of the battery pack. Since it is at the far end of the cable, it can't be mounted on the helmet. It will have to go inside my water pack with the battery unit, which has a very short connector.