beamshot comparisons
 

A big beamshot comparison from a German MTB forum (both links have the same images; AFAIK the fenix lights are not the newest models). Makes one appreciate the huge differences.

http://www.mtb-news.de/forum/showthr...302353&page=15
http://picasaweb.google.de/Ghostdriv...rgleichMTBNews

Why do I get the feeling the newest and best lights are all coming out of europe?

Fantastic beamshot collection! Kudos!

70 watts... lol. Way to blind motorists.

Most of those look like car lights adapted for a bicycle.

Great study on halogen over-volting! He goes from 10-20V on a 20W 12V lamp. You can clearly see the benefits of over-volting to at least 14V, but it gets even better at 16 and 18, not to mention 20V which looks as good as maybe even better than the Lupine Betty! I'm definitely going to go to 16V (at least) for my helmet light setup after seeing this.

I have a 35watt, 12 volt MR11 lamp that I am overvolting with a 14.4 battery. The amount of light is probably the same as a car high beam but the light only lasts for about an hour. I believe I am getting around 1200 lumens.

Careful about overvolting. The brightest light in the world is no good if it's dead. Overvolting drastically shortens bulb life. So when one considers the cost of extra bulbs (financially and environmentally), not to mention the inconvenience of having bulbs die in the middle of a ride, it might not be such a great idea. The money might be better spent simply getting a brighter light to start with.

Who cares? They will still last hundreds of hours and only cost a few bucks each.

The Golf Xenon Abblend is the only one that makes sense, IMO, if it's going to be taken where other people might approach. Lots of light, fat, nearly-uniform beam spread, but a good, clean cutoff to keep from blinding onlookers.

(googled some more...)

Oh, of course -- it's a headlight from a VW Golf! How could I think that bicycle headlights are actually progressing in any way besides outright -- and increasingly abusive -- brightness...

Car headlights don't blind you if they are aimed properly, a similar bike headlight won't either. I know, I use a GE 4509 100 watt spot/flood light and have commuted past police twice with the light on. No problems. Other then the 10 lb SLA only lasting an hour.

Because a light going out at an inconvenient moment (like during a 40mph downhill) can be a really really bad thing.

That's stupid. So that can't happen with lights that are not overvolted? HAHA!

Halogen bulbs normally blow out at the moment of turn-on (cold, low resistance --> more current flow etc.), so just don't turn it off and on during dangerous descents!

That was what I thought back when I tried using 5 NiMH cells for a bulb designed for 4 alkalines. I thought 1.2 x 5 = 1.5 x 4 = 6 V anyway. Turns out the bulbs designed for 4 alkalines are actually rated closer to 5.3 V or so. My light worked, but would burn out in the middle of rides.

Yes they will -- I've nearly fallen off the path while walking and getting hit by really-bright bike headlights. Starting at about twenty feet away, when being approached by a good, bright bike light on a dark path, I can't see anything besides the light itself.

And, "a similar bike headlight" isn't a valid phrase, either. I've only heard about one bike light that has a beam cutoff; all the rest are unblocked. Comparing bike lights to car headlights would be proper only if you're comparing them to high beam car lights.

Automotive low beams are required to have a cutoff pattern at about headlight level with a slight upwards flare towards the side of the road opposite of traffic (to the left for UK/Japan, to the right for everyone else). High beams are really only slightly brighter but without any cutoff.

There are lots of bike lights with beam "cut offs"... maybe not in your LBS(not in mine) ...check out the shaped beam patterns here...

http://www.fa-technik.adfc.de/Kompon.../vergleich.htm

Its amazing how effective a 3w dynamo halogen can be if the light is pointed into the right places.
I don't know why we don't see these lights more often outside of europe.

just ignore that yamcha guy...all he does is cause trouble...check out all his postings :eek:

don't stare at the light then

Another interesting thing about high beams is that they are always halogen lights, even if the low beams on the car are HID. Seems obvious (need to have instant turn-on, etc.), but I never really thought about it until I drove a car with HID headlights. I don't like the two different colors though; I can't wait until all car headlights (plus high beams) are LED-based.

The trouble is, it only takes one glance to screw up someone's night vision. After that, even if I block the light with my hand, I can only see half as well as I could just a minute earlier.

I've been overvolting halogens for nearly 20 years and it's not really a problem with properly designed MR-11 or MR-16 bulbs. I used to overvolt 6V halogen bulbs (HPR-51) and popped those all the time (but only at power-up). About 15 years ago, I started to use MR-11s. I've popped exactly one bulb a year ago upon power-up and never while riding. But I always carry more then one light source anyway.

I suspect that your light burned out during rides because of a loose connection rather then because of the bulb.

My bulbs were Maglite Krypton star 4 cell ones, so yes they're not as tough as the MR-11s. I'm not sure what you mean by loose connections though. I checked the bulbs with a voltmeter after arriving home, and what I found was that something had happened with the potted base that was keeping current from reaching the filament. Perhaps it's a case of the base being unable to stand the overvolting?

The thing is, after switching to a slightly undervolted 5 cell Magnum star, I have had no problems over the course of almost two years. A slight undervolting works wonders with bulb life :D.

Bayonet mount bulbs like the Krypton ones can rattle around in the base. As you ride the light can bounce in and out of the base and lose monetary contact with the battery. It's like turning the light one and off constantly. As others have noted that's when most bulbs burn out.

The MR bases are pins that plug into a socket. They don't bounce around much.

Undervolting halogens is probably worse then overvolting. (Your bulb isn't a halogen.) Halogen needs the temperature to get the cycle going.

Interesting hypothesis. I still don't get though why the Krypton stars died in a few days, while my slightly undervolted Magnum star is alive two years later. Shouldn't they both have the issue with the rattling around the base?

Here's an idea. Could it be that the bulb bases are somehow intentionally built so that any overvolting will burn out some part of it as a safety measure? I can see how the company would rather have people lose a bulb than suffer any explosion.

With regard to undervolting halogens, yes I share your concern with making sure the halogen cycle runs. I know I'm not running a halogen (although seeing how the bulb surface still looks clear, I don't know if the Maglite bulbs have some halogen content or not). I'm thinking how a slight undervolting (say at 95% of rated voltage) can lengthen lamp life tremendously, while probably still having the halogen cycle operate.

I would suspect that the Magnum Star bulb has a thicker filament based on the price differential. Thicker filament means longer life.

I doubt that the bulbs have anything as a safety measure built into them. They are pretty simple mechanisms. It'd be pretty hard to explode one even if you overvolted by a huge amount. The glass bulb on most any lamp is pretty tough.

You might get longer life out of a bulb...even a halogen...by slightly undervolting it, but you'd suffer a significantly dimmer light. I'd rather risk bulb failure and get twice as much light for a 10th of the time than worry about saving money on bulbs. Halogen bulbs are cheap and, from my experience, long lasting. I always carry more than one lamp anyway so the chances of having more then one fail on a ride to work is pretty slim. Even then I carry 2 more back up light sources. Better safe than sorry;)

My overvolting experience was poor.

at 12 volts, my MR11 20 watt 12 volt bulb never died after maybe 1000hrs.

at 14.4 volts, it died in a week. Replacement bulbs lasted maybe 5-100 hrs. I used several brands, no real difference.

the light was awesome. But, contrary to other's assertions, the bulbs always burnt out in the middle of the ride, while being used.

ah well....