To start off with let me state that this post isn’t intended to criticize or promote any manufacturer of bicycle headlights in particular. I’d like to simply point out that most light designs are simply not bicycle specific enough – and particularly not well suited to bicycling in the city.

Safe driving at night relies not only on good vehicle lighting but is also dependent on reflective road signs, high visibility striping, streetlights, and the lights of other drivers on the road. An unlit, unmarked section of road greatly reduces visibility and calls for increased lighting or reduced speed or both. That’s true for cars, motorcycles, heavy vehicles and bicycles.

The use of off-road lighting is illegal on public roads, and one of my issues is that too many lights marketed as bike lights fall into exactly that category, having no beam cut-off. On top of that, although on a bicycle adequate near lighting is critical and extreme headlight reach is a waste of lumens, there needs to be a reasonable balance.

There’s actually a logic to automotive restrictions: a low beam cut-off avoids blinding on-coming traffic and low-beams typically have a reach of about 45 m (145ft). That covers the safety end of things since the braking distance of an automobile with a velocity of 60km/h is about 40 m. So within city limits where the speed limits are a max of 50km/h – that makes sense for motor vehicles.

So what about bicycles? Since some riders will hit 50km/h (30mph), and it would typically take about 45 to 50 ft to stop at that speed, I’d personally like a light that would cover at least a 50ft range and still wouldn’t be offensive to oncoming traffic. But that’s easier said than done.

Anyway, I stuck a pair of 10W LEDs on a bike and let me state up front - these are OFF-ROAD lights. They’re marketed for use on motorcycles, yachts, ATVs, law enforcement vehicles, and heavy equipment. However the reflectors, lumen output and technology is similar to many lights marketed for bicycles. And since they're rated at around 750 lumens each - they're not nearly as potent as some of whats being pushed for bicycles.

This particular installation was done for personal use based on MY usage of the bike, some peculiarities of some of the components, and some components I already had on hand. It wouldn’t necessarily be as practical for another bicycle set up differently. The fork design on this particular bike compresses on lock-out so the beam pattern will drop to an approximate ‘legal’ configuration when lock-out is selected and reverts to off-road mode when the lock-out is released.

So I can live with this light configuration simply because the bike is primarily intended for trails. But it’s a waste of lumens if just for the city.

Motor vehicle headlights need to meet DOT and SAE requirements both for build and installation. So I tried to approximate some of those beam aiming requirements to make the light output ‘street legal’ and avoid blinding on-coming traffic.

The light output from these is pretty good. Under an overhead light in the parking lot the beam is still visible.

But I'm not going to waste a lot of time on beam shots - I'll post some links to sites where that's already been done. These have been around for awhile but although this link is about 3 years old the beam patterns are still representative.
http://www.pirate4x4.com/forum/showthread.php?t=825971j

So using a wall at a distance of 25 feet as a target, the light was aimed downwards till the upper beam edge was no more than 36in off the ground. At that point the light dumped over 50% of the lamp output within the first 30 ft. A real waste of lumens because any of these will easily reach out to over 150 ft if aimed as intended - for off-road use.

Mounting twin lights dosn't change the overall reach much. The issue isn't lack of lumens.

Forcing the light into a ‘legal’ configuration using a fork mount meant the beam centre was at a distance of 11 feet with a 35 degree lens, a distance of 17 feet using a 15 degree lens and a distance of 30 feet using a 10 degree lens. Using 10 degree spots on the forks gave an effective reach out to maybe 50 feet.




I did manage to fabricate a helmet mount for these and using a helmet mount not only gave better reach – it of course enabled me to actively move the beam centre (for my benefit and that of on-coming traffic) and of course is why most riders prefer a helmet mount. If I had to choose – a helmet mount is the best choice for the city. The absolute best combination was using two elliptical (15/45) lenses on the forks which moved the beam center out to 17 feet, still gave coverage at 7 feet but give broader coverage out to 55 feet. Adding a Helmet mounted 10 deg spot will augment light from 35 to 60 ft and pick out signage a couple blocks away. But I still have a lot of wasted lumens.

There's a lake out back and I'll be testing these more completely over the next month or so.

Shaped lenses and a more intelligent overall design means fewer lumens will do a better job. Currently the Phillips elliptical design and units like B&M imported from Germany are among the few lights that seem to do that – probably because government regulations there give them no choice. I’d like to see much better battery life and run times myself and still have good lighting. I know it’s possible because I can get over 8 hrs run time myself with this set-up using just one bottle cage. But I also intentionally left out a lot of ‘consumer features’ on this set-up that were of no interest to me.

DOT approved LED head lights are currently being produced for automobiles, and they incorporate several separate LEDs and lenses so that the individual high and low beams have different focusing distances and intensities. That’s very different from a simple dimmer. But at the moment they’re automotive size and too big for my uses. Which is why I was particularly interested in the DesignShine model, because apparently the design combines all of those: shaped lenses, a variety of LEDs with different intensities and focusing cones, and selectable intensities. I’m hoping we’ll see more products like that in the future. Probably the only way that’ll happen is if enough people decide they’re not happy with the currently available designs.

I also drive a car myself and really don't like the idea of possibly having to deal with something like this:

There's 1,500W of light illuminating the BACKGROUND in this photo and I still had to stop down the camera to avoid having the headlights completely burn out the shot. Strongly focused lights with narrow beams put some intense light in a small area and can be a major problem in traffic if used without some discretion. In California, I believe these are already illegal for use as running lights on motorcycles.

So what about those 900 and 1,400 lumen bike lights? Not a criticism - just a concern.