Why not generator lights?

[Joshua Putnam]

In article <[email protected]>,
[email protected] says...

> Does expectation matter more than the brightness that people
> are debating?


Yes. See e.g. the problems of motorcycles with two headlights
relatively close together -- motorists often mistake this for car
headlights that are far away, and cut in front of the motorcyclist.

> That is, even though drivers would see the slow car or
> bicycle at the same distance if both were using minimum code
> bicycle lights, they would avoid the bicycle and smash into
> the car?

If the car had one bike light dead center, then a person using that
light as a cue would definitely run into the car. If the car had its
one light on the far left side of the car, then someone using that light
as a cue would be driving far enough left to miss the car.

Note the brilliant reflective tape outlines on commercial trucks -- a
fairly small reflector would provide visibility, but the tape stripes
define the outline so people recognize the nature of the object, rather
than just its presence.

> What do you think about slow motorcycles? Same signature as
> bicycles, but I suspect that they have much higher lighting
> requirements. Is it just the blinking?

My old Honda, from back in the days of 6 volt motorcycle wiring, had a
tail light barely brighter than a bicycle light. But it was immediately
recognizeable as a motorcycle because of the pulsing of the light. Now
that motorcycles usually have charging systems just as stable as cars,
many riders add back that magneto pulse artificially, to improve
recognition.

--
[email protected] is Joshua Putnam
<http://www.phred.org/~josh/>
Updated Bicycle Touring Books List:
<http://www.phred.org/~josh/bike/tourbooks.html>

 

[Joshua Putnam]

It occurs to me that, as someone who accounted for two of your edge
cases, I might say that I find my current lighting system more than
adequate for urban and suburban riding. 3W generator hub with Lumotec
in the front; in back, a 3" amber round reflector and a 5-LED Vistalite.
In fog, I add a Xenon strobe in back.

Having compared them in many conditions, both on a bike and in a car, I
find the automotive-style reflector far better than the bicycle-specific
ones that have only a third of their surface area aimed at overtaking
traffic. By the light of a 3W generator, my reflector is readily
visible at a quarter mile in clear weather.

I also like reflective glove backs -- they make hand signals much easier
to see, especially on rainy nights.

--
[email protected] is Joshua Putnam
<http://www.phred.org/~josh/>
Updated Bicycle Touring Books List:
<http://www.phred.org/~josh/bike/tourbooks.html>

 

[David Damerell]

begin quoting Patrick Lamb <[email protected]>:
><[email protected]> wrote:
>>[Patrick; the significant difference is between "lights" and "no lights",
>>even when "lights" includes sub-legal setups like yellow front blinkies.]
>I'd venture to disagree with you there

I am not stating my opinion there. I am summarising the results the
Transport Research Laboratory discovered. They are somewhat
counterintuitive, I agree.

>>begin quoting Steven M. Scharf <[email protected]>:
>>>You can see the observations of various cycling experts (Kifer,
>>It's easy to put words into the mouths of the dead; but tell me, what
>>lights did Ken Kifer actually _use_?
[of course I knew the answer to this all along]
>So Ken used a generator light, one of the older versions without an
>LED standlight, and found it adequate for most of his riding.

Clearly he found it adequate for all of his riding.
--
David Damerell <[email protected]> Kill the tomato!

 

[Patrick Lamb]

Steven M. Scharf wrote:
> Patrick Lamb wrote:
>
>> So Ken used a generator light, one of the older versions without an
>> LED standlight, and found it adequate for most of his riding.
>
>
> That was one of Ken's great attributes. He could use a product, yet
> recognize its limitations and clearly state them. As he stated, "a
> generator light is not very bright in city traffic." I did not put words
> into anyone's mouth.

Ken was ambiguous on this, I'll grant you. But despite noting that the
light wasn't very bright, he never owned nor used what he called a
"water bottle battery." Perusing his site, it looks to me like the AA
headlights were too dim for him, but he was comfortable with his
generator-powered setup.

Pat

 

[Andy M-S]

Joshua Putnam wrote:
> It occurs to me that, as someone who accounted for two of your edge
> cases, I might say that I find my current lighting system more than
> adequate for urban and suburban riding. 3W generator hub with
Lumotec
> in the front; in back, a 3" amber round reflector and a 5-LED
Vistalite.
> In fog, I add a Xenon strobe in back.

I'm about to join the hub generator generation (it's at my LBS right
now). For the past couple of years, I used a pair of 5w Nighthawk
lights, and sometimes a 5w/10w setup. It was pretty good--with a pair
of smart chargers, one at work and one at home, charging wasn't even
much of an issue. Then, having two bikes and just for the heck of it,
I got a BiSy light head and a BB generator to try out.

I was surprised at how bright the BiSy was. Initially, I attributed
this to the generator putting out a lot of extra voltage, but then I
ran the same light off batteries (because the BB generator slipped in
the wet) and I became convinced that it had more to do with reflector
and aperature size.

Many SLA-powered headlights use bulbs with tiny reflectors and small
(c. 1") aperatures. The BiSy has a huge reflector and a 3" (approx)
aperature. The result is that you get a much higher return on your
power.

I don't know if the 3w BiSy can compare to a 10w SLA system, but I
think it's certainly brighter than the 5w single and/or dual systems I
have used. I plan to have a white LED blinky in front for a
standlight, and I *may* end up using an old CatEye helmet-mounted
light with some surplus Li-Ion batteries I have, but I'm looking
forward to having basic light readily available, no batteries required.

 

[Frank Krygowski]

[email protected] wrote:

> On Tue, 04 Jan 2005 23:13:28 -0500, Frank Krygowski
> <[email protected]> wrote:
>
>
>>[email protected] wrote:
>>
>>
>>>On Tue, 04 Jan 2005 11:41:18 -0500, Frank Krygowski
>>><[email protected]> wrote:
>>>
>>>[snip]
>>>
>>>
>>>
>>>>I think Scharf's making progress. He may now understand that cars do
>>>>have reflectors (now that I've pointed it out to him).
>>>
>>>
>>>Dear Frank,
>>>
>>>I expect that this has been discussed, but I don't recall
>>>seeing much about it.
>>>
>>>If bicycle lights that meet minimum requirements are
>>>perfectly adequate for such small vehicles generally going
>>>slower than traffic, should they also be adequate for cars
>>>going as slowly in traffic?
>>>
>>>If so, why are slow-moving cars usually adorned with
>>>extremely bright flashing lights and huge orange warning
>>>triangles?
>>>
>>>Carl Fogel
>>
>>Actually, bikes do have an advantage or two in this regard. First, they
>>are easier to avoid because of their narrowness. Second, nearly all
>>night bikes have moving reflectors on pedals and/or wheels, or
>>(recently) twinking LEDs. The changing pattern of these devices gives
>>more conspicuity, plus a well-recognized signal that a bicycle is ahead
>>- as opposed to a reflectorized mailbox.
>>
>>But there is a good test of your idea. Amish buggies abound within 30
>>miles of my house. I know by experience that they usually move somewhat
>>slower than cycling enthusiasts. (It's fun to race them.) They are
>>used at all hours of day and night.
>>
>>They typically use lights that appear similar to, or dimmer than, car
>>taillights. And I know they have problems with nighttime car-buggy
>>collisions. But I don't know the data on collision frequency versus
>>that of cars & bikes. Perhaps you'd like to search for that?
>>
>>It may be that Amish buggies would benefit from LED blinkies, or from
>>moving reflectors on their wheels. They could be made to reflect
>>backwards, not merely to the (less useful) sides.
>>
>>The problem is that Amish attitudes are (to me, anyway) very
>>unpredictable. Amish rules vary parish by parish, from what I've been
>>told by their neighbors, etc. Some parishes have fought valiantly to
>>avoid requirements for reflective "slow moving vehicle" triangles, for
>>religious reasons. OTOH, I was told of one parish that allowed its
>>members to drive cars, as long as the cars were used only for
>>work-related transportation and were painted completely black, including
>>the "chrome" parts.
>
>
> Dear Frank,
>
> This recent article came to mind, so I looked it up:
>
> http://www.chieftain.com/life/1104576681/1
>
> Damned if I can tell whether it was dark when the truck hit
> the buggy from behind and killed the pregnant Amish mother
> and her son--a good example of bad reporting.

Look at the purpose of the article. The reporter was writing about the
human and sociological aspects of the situation. He wasn't interested
in the safety details. We may complain about the lack of detail on
lighting conditions, while someone else may be offended that they didn't
describe what happened to the horse! I'd say the article's subject is
the reporter's (and his editor's) decision.


> An unrelated point occurs to me. If minimum code bicycle or
> even car lights are perfectly adequate, why do we spend
> enormous amounts of money on street lights?

Carl, it's a "perfectly adequate" thing so much as a cost-benefit thing,
like most decisions. And the benefits of street lights are not only for
motorists and cyclists. They're put up to aid pedestrians and for
neighborhood security as well. After all, street lamps predate
automobiles, and even predate electric lighting.

We're not going to achieve perfection in this world, so we seek a
cost-benefit balance. And when choosing the cost-benefit balance for
vehicle lights, I see no reason a vehicle with a typical top speed of 20
mph should have headlights like a 90 mph car or a 160 mph motorcycle.

--
Frank Krygowski [To reply, remove rodent and vegetable dot com.
Substitute cc dot ysu dot
edu]

 

[Frank Krygowski]

Steven M. Scharf wrote:

> Patrick Lamb wrote:
>
>> So Ken used a generator light, one of the older versions without an
>> LED standlight, and found it adequate for most of his riding.
>
>
> That was one of Ken's great attributes. He could use a product, yet
> recognize its limitations and clearly state them. As he stated, "a
> generator light is not very bright in city traffic." I did not put words
> into anyone's mouth.

Ken was a smart guy. We corresponded extensively, we worked together on
some projects, and my wife and I just missed having him as a house guest.

AFAIK, the only light he used with any regularity was a generator light.
His "not _very_ bright" statement above should not be read as "not
_sufficiently_ bright." That's not what he said.

I'll also point out that Ken lived literally in the Alabama woods.
Personally, I think if he'd moved to a city (which would have been
terrible for him) he'd have soon gained enough experience with generator
lights to consider them the best system for city use, as well.

After all, city riding is the situation most generator lights are used
for. Many generator users posting here are primarily city & suburb
riders. And of course, Joe Breezer seems to agree. See his city bikes
at http://www.breezerbikes.com/bikes-town.html

As we've mentioned many times before, it's possible to dig up anonymous
quotes made by obscure folks who share Scharf's views. It's possible to
make much of a Ken Kifer quote that's taken out of context. But
contrary to Scharf's contention, the great majority of prominent cycling
experts are perfectly fine with generator lights. Those who don't know
John Forester, John Franklin, John Schubert, John Allen, and Riley Geary
might do well to learn about them, and about what lighting systems they
approve of. For example, to see what Forester uses, visit
http://www.johnforester.com/Articles/Lights/cpsc9601.htm and scroll to
the picture at the very bottom.

In the meantime, it's good to remember that generator lights meet the
legal requirement of every governing body on earth, AFAIK, including the
"Everything is dangerous" people at the Consumer Products Safety Commission.

--
Frank Krygowski [To reply, remove rodent and vegetable dot com.
Substitute cc dot ysu dot
edu]

 

[[email protected]]

On Tue, 4 Jan 2005 22:44:13 -0800, Joshua Putnam
<[email protected]> wrote:

[snip]

>My old Honda, from back in the days of 6 volt motorcycle wiring, had a
>tail light barely brighter than a bicycle light. But it was immediately
>recognizeable as a motorcycle because of the pulsing of the light. Now
>that motorcycles usually have charging systems just as stable as cars,
>many riders add back that magneto pulse artificially, to improve
>recognition.

Dear Josh,

Perhaps while stopped and idling? The head and tail lights
on the 1976 no-battery trials Hondas that a friend and I
ride don't seem to pulse noticeably above idling rpm.

Certainly they pulse nothing like the interesting blue-white
flickering of a lonely bicycle headlight that I saw a few
weeks ago, which I assumed (perhaps mistakenly) was a
generator light. It was the only lighted bicycle that I
remember seeing at night last year--the unlighted ones are
more numerous and may be more memorable at night for obvious
reasons.

Carl Fogel

 

[[email protected]]

On Wed, 05 Jan 2005 11:31:49 -0500, Frank Krygowski
<[email protected]> wrote:

[snip]

>Carl, it's not a "perfectly adequate" thing so much as a cost-benefit thing,
>like most decisions. And the benefits of street lights are not only for
>motorists and cyclists. They're put up to aid pedestrians and for
>neighborhood security as well. After all, street lamps predate
>automobiles, and even predate electric lighting.
>
>We're not going to achieve perfection in this world, so we seek a
>cost-benefit balance. And when choosing the cost-benefit balance for
>vehicle lights, I see no reason a vehicle with a typical top speed of 20
>mph should have headlights like a 90 mph car or a 160 mph motorcycle.

Dear Frank,

Actually, I'm wondering about tail lights.

Where I live, the well-lit streets are used almost
exclusively by cars at night, not pedestrians or bicyclists,
Even in the countryside, lonely 25 mph intersections are lit
for cars that can do 90 mph.

My daily ride runs through an S-bend gully that cuts down
from through the prairie bluffs. A handsome street light
illuminates the first curve all night long. There is no
neighborhood, no intersection, no likelihood of pedestrians.
Looking out the odd view from my back window, I can see it
peeping up from the gully, half a mile away.

It may be that good lights cost too much on bicycles. Much
better lights are put up at considerable cost to "aid"
almost non-existent pedestrians who could walk just fine and
find their way with much dimmer lights, quite safely on
sidewalks.

Carl Fogel

 

[Frank Krygowski]

[email protected] wrote:

>
>
> It may be that good lights cost too much on bicycles.

Not IMO. After many tests and a few spontaneous compliments, I
confidently rate my bicycle's lights as much better than merely "good."
And they've not been expensive. Current prices for the lights and
reflectors I normally use on my commuter would probably be no more than
$50. (Much of it is quite old.)

Much
> better lights are put up at considerable cost to "aid"
> almost non-existent pedestrians who could walk just fine and
> find their way with much dimmer lights, quite safely on
> sidewalks.

That paragraph raises two thoughts, which are in some conflict.

First, I'm wary of any hint that we should not accommodate "almost
non-existent pedestrians." That's the thinking that allowed highway
engineers to build a freeway overpass bridge near my home, which is very
hostile to pedestrians. No sidewalks, and close-passing high speed
traffic. That bridge forms a fearsome barrier between a large shopping
area and nearby residences, and helps perpetuate the idea that people
won't walk anyway. And there are countless other examples in the
commercial/shopping zoo that's beyond that bridge.

But OTOH, I'm a fan of the night sky, and I'm consequently not a big fan
of outdoor lighting! My preferred pedestrian lighting would be a
hand-carried flashlight. Second choice might be downward focused,
low-intensity lights that are not high off the ground. Path lighting, I
suppose.

However, I notice that my priorities tend to differ from those of the
rest of society. ;-)


--
Frank Krygowski [To reply, remove rodent and vegetable dot com.
Substitute cc dot ysu dot
edu]

 

[Tim McNamara]

Joshua Putnam <[email protected]> writes:

> In article <[email protected]>,
> [email protected] says...
>
>> Does expectation matter more than the brightness that people are
>> debating?
>
> Yes. See e.g. the problems of motorcycles with two headlights
> relatively close together -- motorists often mistake this for car
> headlights that are far away, and cut in front of the motorcyclist.

I have seen this exact situation from the driver's seat and only
momentarily made that confusion. There is much more visual
information available regarding estimating distance (a function of
depth perception) and time to contact (perception of relative motion)
than just how far apart the headlights are. It is an inattentive
driver that would fail to see this situation for what it is within a
very short time frame. Unfortunately many drivers are inattentive,
and even attentive drivers can be fooled if visual information is
severely limited.

Depth perception is not dependent on binocular vision, contrary to
common myth. Indeed, binocular vision ceases to be a factor in depth
perception when objects are not all that far away (150 meters, if
memory serves, is the limit of binocular vision as a significant
component of depth perception). The main tool in estimating distance
is seeing the separation along the ground between the viewer and the
base of the object. When we have access to that information, we tend
to be able to judge not only distance but size of the object with very
good accuracy.

Night, of course, removes much of this information but headlights,
shining on the ground, have the effect of allowing us to see the
ground separating us from the oncoming vehicle- but not as well as
daylight, of course. Two motorcycles, side by side, should illuminate
the ground in front of them with their headlights, as well as the
driver's own headlights, making it possible to judge distance and time
to contact fairly well.

This is why high-mounted headlights, which tend to cast a short,
bright pool of light, are less helpful than a lower mounted light with
a longer pool of ess intense illumination. The lower light also shows
the texture of the ground better.

>> That is, even though drivers would see the slow car or bicycle at
>> the same distance if both were using minimum code bicycle lights,
>> they would avoid the bicycle and smash into the car?
>
> If the car had one bike light dead center, then a person using that
> light as a cue would definitely run into the car. If the car had
> its one light on the far left side of the car, then someone using
> that light as a cue would be driving far enough left to miss the
> car.

Here you've changed one of the visual cues- how bright the oncoming
light is- but that is not the only cue. There is still relative
motion to use as part of the perceptual process. You've also changed
the physical information by putting the light in different places on
the front of the car. I'm not sure that's a good illustration of
your point.

> Note the brilliant reflective tape outlines on commercial trucks --
> a fairly small reflector would provide visibility, but the tape
> stripes define the outline so people recognize the nature of the
> object, rather than just its presence.

Again providing more information to be perceived, although one could
also fake it and put a semi-sized reflective wire frame on a
bicycle...

>> What do you think about slow motorcycles? Same signature as
>> bicycles, but I suspect that they have much higher lighting
>> requirements. Is it just the blinking?
>
> My old Honda, from back in the days of 6 volt motorcycle wiring, had
> a tail light barely brighter than a bicycle light. But it was
> immediately recognizeable as a motorcycle because of the pulsing of
> the light. Now that motorcycles usually have charging systems just
> as stable as cars, many riders add back that magneto pulse
> artificially, to improve recognition.

We haven't talked about perceptual learning in this context. Drivers
do learn what certain objects look like at night: trucks, cars,
motorcycles, bicycles, etc all provide different information. The
size of the light, its brightness, height above the road surface,
relative motion (bikes tend to wobble more than motorcycles or cars,
for example), apparent velocity, closing speed, etc all are sources
of information that the attentive driver uses to perceive the world
he or she is driving through.

 

[[email protected]]

On Wed, 05 Jan 2005 17:52:19 -0600, Tim McNamara
<[email protected]> wrote:

>Joshua Putnam <[email protected]> writes:
>
>> In article <[email protected]>,
>> [email protected] says...
>>
>>> Does expectation matter more than the brightness that people are
>>> debating?
>>
>> Yes. See e.g. the problems of motorcycles with two headlights
>> relatively close together -- motorists often mistake this for car
>> headlights that are far away, and cut in front of the motorcyclist.
>
>I have seen this exact situation from the driver's seat and only
>momentarily made that confusion. There is much more visual
>information available regarding estimating distance (a function of
>depth perception) and time to contact (perception of relative motion)
>than just how far apart the headlights are. It is an inattentive
>driver that would fail to see this situation for what it is within a
>very short time frame. Unfortunately many drivers are inattentive,
>and even attentive drivers can be fooled if visual information is
>severely limited.
>
>Depth perception is not dependent on binocular vision, contrary to
>common myth. Indeed, binocular vision ceases to be a factor in depth
>perception when objects are not all that far away (150 meters, if
>memory serves, is the limit of binocular vision as a significant
>component of depth perception). The main tool in estimating distance
>is seeing the separation along the ground between the viewer and the
>base of the object. When we have access to that information, we tend
>to be able to judge not only distance but size of the object with very
>good accuracy.
>
>Night, of course, removes much of this information but headlights,
>shining on the ground, have the effect of allowing us to see the
>ground separating us from the oncoming vehicle- but not as well as
>daylight, of course. Two motorcycles, side by side, should illuminate
>the ground in front of them with their headlights, as well as the
>driver's own headlights, making it possible to judge distance and time
>to contact fairly well.
>
>This is why high-mounted headlights, which tend to cast a short,
>bright pool of light, are less helpful than a lower mounted light with
>a longer pool of ess intense illumination. The lower light also shows
>the texture of the ground better.
>
>>> That is, even though drivers would see the slow car or bicycle at
>>> the same distance if both were using minimum code bicycle lights,
>>> they would avoid the bicycle and smash into the car?
>>
>> If the car had one bike light dead center, then a person using that
>> light as a cue would definitely run into the car. If the car had
>> its one light on the far left side of the car, then someone using
>> that light as a cue would be driving far enough left to miss the
>> car.
>
>Here you've changed one of the visual cues- how bright the oncoming
>light is- but that is not the only cue. There is still relative
>motion to use as part of the perceptual process. You've also changed
>the physical information by putting the light in different places on
>the front of the car. I'm not sure that's a good illustration of
>your point.
>
>> Note the brilliant reflective tape outlines on commercial trucks --
>> a fairly small reflector would provide visibility, but the tape
>> stripes define the outline so people recognize the nature of the
>> object, rather than just its presence.
>
>Again providing more information to be perceived, although one could
>also fake it and put a semi-sized reflective wire frame on a
>bicycle...
>
>>> What do you think about slow motorcycles? Same signature as
>>> bicycles, but I suspect that they have much higher lighting
>>> requirements. Is it just the blinking?
>>
>> My old Honda, from back in the days of 6 volt motorcycle wiring, had
>> a tail light barely brighter than a bicycle light. But it was
>> immediately recognizeable as a motorcycle because of the pulsing of
>> the light. Now that motorcycles usually have charging systems just
>> as stable as cars, many riders add back that magneto pulse
>> artificially, to improve recognition.
>
>We haven't talked about perceptual learning in this context. Drivers
>do learn what certain objects look like at night: trucks, cars,
>motorcycles, bicycles, etc all provide different information. The
>size of the light, its brightness, height above the road surface,
>relative motion (bikes tend to wobble more than motorcycles or cars,
>for example), apparent velocity, closing speed, etc all are sources
>of information that the attentive driver uses to perceive the world
>he or she is driving through.

Dear Tim,

You're right about perceptual learning. On one long curve on
my daily ride, I often have fun trying to decide whether the
distant figures obscured from the waist down by brush are
walking, skating, or bicycling.

The distance and the angle makes it impossible to see a
bicycle or judge the speed, so there's just the faint
impression of motion.

Generally, I distinguish walkers first from skaters and
bicycles, and then have to get closer to see whether they're
skating or riding.

It's a little like trying to decide if that distant
bicyclist whom you're overtaking is a man or a woman. We can
often tell long before it seems possible (though some riders
may leave you wondering even after you pass them).

To return to the night illumination question, it's curious
that so much more illumination seems to be so highly desired
by everyone else at night besides some bicyclists--judging
by cars and motorcycles and street lighting, more light is
definitely better because it improves all the other visual
cues that we use during daylight.

I suppose that vampires argue about whether two glowing red
eyes are plenty or whether adding a lit cigarette would be a
good idea.

Carl Fogel

 

[Tom Sherman]

Frank Krygowski wrote:

> ...
> But OTOH, I'm a fan of the night sky, and I'm consequently not a big fan
> of outdoor lighting! My preferred pedestrian lighting would be a
> hand-carried flashlight. Second choice might be downward focused,
> low-intensity lights that are not high off the ground. Path lighting, I
> suppose.
>
> However, I notice that my priorities tend to differ from those of the
> rest of society. ;-)

My preferred pedestrian lighting is none.

--
Tom Sherman - Near Rock Island

 

[Frank Krygowski]

[email protected] wrote:

>
> To return to the night illumination question, it's curious
> that so much more illumination seems to be so highly desired
> by everyone else at night besides some bicyclists--judging
> by cars and motorcycles and street lighting, more light is
> definitely better because it improves all the other visual
> cues that we use during daylight.

Again, it's a cost-benefit thing. And "everyone else" isn't really
correct - it's not universal.

Most of what people spend money on is determined by fashion. (How else
to explain SUV popularity, for example?) Currently, extra fog lights
and driving lights are fashionable on cars and trucks. People are
willing to increase their vehicle's price by a tiny percentage to get
those fashionable lights - and now, many drivers don't even have the
choice. Our new Pontiac Vibe came with fog lights that I don't want and
have never needed to use. But if I do turn them on, the cost is
effectively zero.

With bikes, it's different. More light almost always has _some_
increased cost. In many cases, it's a combination of initial price,
recharging hassle, limited run time, battery replacement cost, and added
weight. For some - like night single track riders - those costs are
less than the benefit of being able to ride and/or race at all hours,
especially when there are no alternatives.

For me, brighter lights are not necessary. There may be instances where
they'd be somewhat desirable, but those are rare enough that the benefit
is overbalanced by the detriments I listed.

In fact, this is true despite the fact that I own two different
rechargeable setups. I've already absorbed the first cost (or, in one
case, fabrication time) and I still have to periodically recharge to
keep the batteries from suiciding, but they're just not worth hauling
around in case I might need them. My generator set makes them superfluous.


--
--------------------+
Frank Krygowski [To reply, remove rodent and vegetable dot com,
replace with cc.ysu dot edu]

 

[Steven M. Scharf]

[email protected] wrote:

> What do you think about slow motorcycles? Same signature as
> bicycles, but I suspect that they have much higher lighting
> requirements. Is it just the blinking?

The conspicuity studies on motorcycles show a large increase in
conspicuity as headlight brightness increases. IIRC, it was a 350%
increase in conspicuity for a 50% increase in brightness.

No reason to think that the same would not apply to bicycles.

I think that it’s safe to state that everyone agrees that brighter
lights make a cyclist much more visible, and everyone agrees that with
brighter lights the cyclist can see more of the road, both to the sides
and further ahead.

The issue is really whether or not the hassle of charging batteries is
worth it for the lower expense and greater visibility that these lights
provide.

The subject of this thread would have made more sense had it been
something like “is there a significant advantage in conspicuity in going
beyond the minimum legal requirements for lighting?” But Frank would
never start a thread like that, because all the evidence is against the
conclusion he desires; it’s much more ambiguous to use the poorly
written premise that he chose.

 

[[email protected]]

On Thu, 06 Jan 2005 03:47:28 GMT, "Steven M. Scharf"
<[email protected]> wrote:

>[email protected] wrote:
>
> > What do you think about slow motorcycles? Same signature as
> > bicycles, but I suspect that they have much higher lighting
> > requirements. Is it just the blinking?
>
>The conspicuity studies on motorcycles show a large increase in
>conspicuity as headlight brightness increases. IIRC, it was a 350%
>increase in conspicuity for a 50% increase in brightness.
>
>No reason to think that the same would not apply to bicycles.
>
>I think that it’s safe to state that everyone agrees that brighter
>lights make a cyclist much more visible, and everyone agrees that with
>brighter lights the cyclist can see more of the road, both to the sides
>and further ahead.
>
>The issue is really whether or not the hassle of charging batteries is
>worth it for the lower expense and greater visibility that these lights
>provide.
>
>The subject of this thread would have made more sense had it been
>something like “is there a significant advantage in conspicuity in going
>beyond the minimum legal requirements for lighting?” But Frank would
>never start a thread like that, because all the evidence is against the
>conclusion he desires; it’s much more ambiguous to use the poorly
>written premise that he chose.

Dear Steven,

Purely off-topic, but I occasionally have near accidents on
a nature trail that winds through the woods.

I always feel bad, but I'm also fairly sure that paintball
players wearing head-to-toe hunting camouflage including
gloves and facemasks shouldn't complain if people fail to
notice them about to step onto the path.

Carl Fogel

 

[Steven M. Scharf]

Steven M. Scharf wrote:

<snip>

I should have added, that referenced on my site, is a UK study on
motorcycle lights, "In terms of intensity, Donne and Fulton (1988) found
that for small motorcycles, a 50% increase in headlight power increased
conspicuity distance by 350%; dependent upon beam pattern." This is
valuable data for bicycle conspicuity as well.

The link to this report can be found at
"http://nordicgroup.us/s78/taillights.html"

One other bit of data, is the Chicagoland Bicycle Federation's
conspectus of the Effective Cycling video, which states:

"Riding at night: Lights, lights, lights—headlamp, rear light, and
reflectors. Shows a car driver’s nighttime perspective of various
lighting. Conspicuity setups illustrate that in general, more light is
better. Detection, recognition, avoidance."

So Forester apparently did some conspicuity tests, or found some
somewhere, that reached the (obvious) conclusion that the more light the
better. No real dispute about that conclusion either, even the users of
dynamo lighting readily admit that they are less visible, and can see
less well, than users of higher power lighting, but they feel that the
increases gained by better lights do not add measurably to their safety.
This whole thread was an attempt to prove that the minimum legal
standards are sufficient, and the evidence proves otherwise.

It's too bad there are not any specific studies on bicycle lights which
compare the differences between various degrees of intensity. If a
company such as Night-Sun funded a study, it would be dismissed by
advocates of dynamo lights, and if a company such as Dynosys funded a
study it would be dismissed by advocates of higher power lights!

 

[Steven M. Scharf]

Mark Janeba wrote:

> FWIW, the Kearney barricade flashers I have flash at about twice the
> rate of the old Belt Beacons. I think more than size or brightness, it
> helps because people quickly "recognize" it as a hazard. "People go
> around you like a hole in the road." They *are* large, and mounting is
> a moderate pain; a rear rack is pretty much required.

I find the same behavior with my flashing amber xenon strobe. The
motorist will make a big arc around me, because they expect some sort of
road work or something.

 

[Steven M. Scharf]

Matt O'Toole wrote:

> Not always, and most people aren't up to a task like this.

Supposedly it doesn't always work, though I don't recall that I ever
found a shorted NiCad that I couldn't "fix" with my zapper.

I built a zapper back in 1977, based on the PE article.

Myers, D. C., "Zap New Life into Dead Ni-Cd Batteries," Popular
Electronics, July 1977, pp. 60-61.

 

[Frank Krygowski]

Steven M. Scharf wrote:

>
>
> The subject of this thread would have made more sense had it been
> something like “is there a significant advantage in conspicuity in going
> beyond the minimum legal requirements for lighting?” But Frank would
> never start a thread like that, because all the evidence is against the
> conclusion he desires; it’s much more ambiguous to use the poorly
> written premise that he chose.

If you read the question I posed in the body of the posts, it should be
clear that I was trying ascertain the value of legal lighting - to get
real accounts of what happens in the real world. IOW, I'm trying to
learn what's practically necessary for conspicuity.

The question Scharf proposes above would generate only more trivial
opinions, but nothing practical. We'd hear that doubling the legal
minimum light output would cause more conspicuity. Quadrupling it would
cause even more conspicuity... and so on.

Using Scharf logic, someone would end up recommending infinitely
powerful lights, because "infinity minus one lumen" would be less visible!

Again, I was hoping to get an idea of whether legal lighting was, as
Scharf claims, woefully inadequate. Since he doesn't like the answer we
got, he's now determined to change the question.


--
--------------------+
Frank Krygowski [To reply, remove rodent and vegetable dot com,
replace with cc.ysu dot edu]