Performance

I'm pretty happy with how the light worked out. I got through the 24 hour race, and that was my original aim. It ran happily for four night laps with about 50 minutes of use per lap. I charged the batteries and slept for a few hours, then ran it for another two laps. I had no problems at all, despite two crashes in the night. Even the lenses stayed firmly attached.

I made a mid-race adjustment: a piece of cardboard taped to the top of the head unit. It stops the light from the side of the lenses from messing up my night vision.

My main dissatisfaction with the light is in the lens quality. For what was nominally a six-degree lens, the beam was very loose. To compare this, I photographed each light pointing at my bedroom wall with the same exposure time:

This mountain bike light is on the left, the commute light is on the right. The mountain bike light uses three six-degree Polymer Optics lenses. The commute light uses a single Fraen narrow lens. As you can see, the intensity is about the same, but the Polymer Optics lenses aren't nearly as tight - certainly not what I'd expect from a six degree lens.

There are a few explanations for this. I had some trouble mounting the lenses because I didn't use a PCB, but I got them pretty well aligned in the end. The lenses could simply be junk - but I doubt that they'd be that bad. My current best theory is that my supplier gave me the wrong ones. They also shipped very very late, sent the order to the wrong address, and didn't respond to emails. I won't be ordering from them again...

The fuzzy beam actually works well for mountain biking, since low-speed vision is pretty important (technical trails and the like). I still wanted a nice tight beam for long-distance vision, though. The 24 hour track has an awesome downhill section at the end.

Where to from here? I want lighter and brighter - something I could use in the city. I'd like to not use a bottle cage (for Audax rides) and to be able to use a really small battery (for commuting or club rides) or a really large battery (for Audax, endurance MTB or adventure racing). I'm thinking Lithium Ion batteries and Luxeon K2's, when they become available. Stay tuned!