4W Quad Cree 1W Emitter MR16 Lamp for Dynamo System Project Completed

On Jul 3, 7:04*pm, SMS wrote:
On 03/07/10 3:22 PM, James wrote:

snip

A wide beam angle has the
advantage of throwing light on the motorists waiting to pull out in
front of you, one of the most common hazards I face at night. *In my
particular circumstance, seeing the road is not an issue, being seen
by the motorists is.

I suppose circumstances may differ. However, in my decades of night
riding, I've never had a motorist pull out in front of me, either from
a position waiting for a stop sign, or by making a left turn (here in
the US) from an oncoming position.

In fact, it's clear to me that motorists wait much longer for me when
I'm riding at night than they do in the daytime. From this (and from
spontaneous motorist and pedestrian comments, and from the tests I've
run with volunteers) I've concluded that my generator light is
certainly conspicuous enough.

50 degrees is a bit wide. The problem is that most bicycle dynamo lights
are _far_ too narrow.

Again, the most charitable thing I can say here is that it must depend
on your circumstances. The only time I've wished for a wider beam is
when turning extremely sharp corners at low speed. Now that more
lumens are easily available from a generator set's headlight, that
detail can be taken care of, if someone would design the proper LED
optic unit.*

This is by design because the limited available
light needs to be focused directly on the patch of road in front of the
bicycle, and they need to keep the cost down so the optics are generally
poor.

Sigh As if we haven't been over this befo

Modern headlights designed for generator lights have the best optics
on the bike market. The beams are purposely designed to fit the
requirements of a road vehicle, to give even illumination of the road
surface, sufficient "throw" or light down the road, and sufficient
conspicuity for other road users to notice.

By contrast, MR bulbs are designed to evenly illuminate things like
overhead projectors, artwork displayed on walls, and kitchen
counters. The requirements are NOT the same as those of a road
vehicle, and while they are fine for mountain biking, they do NOT do a
better job on the road.

35 degrees or so of beam spread would be ideal. Fortunately the MR lamps
are available in a very wide choice of beam spreads.

* OK, let's talk optics again. What would be the characteristics of
the ideal headlight beam?

First, it's going to be very similar for either a bicycle, a
motorcycle and a car or truck, differing mostly in power. There is no
need for the headlight of a 25 mph bicycle to be as powerful (in total
lumens) as that of a 75 mph car.

Still, you don't want a bright spot close in front of you and darkness
all around. That ruins your night vision. You should have a fairly
even illumination of the road surface. Due to the position of the
road surface relative to your headlight and your eyes, that means the
light falling close to the front wheel should be dimmer, and that
projecting further down the road should be brighter. The beam
intensity should increase smoothly from bottom to top. The highest
part of the directed beam should be just below the horizon, and should
be noticeably brighter. This is where non-bike-specific beams fail.
They are radially symmetrical, so they tend to be too bright up close,
and/or not bright enough down the road.

A small amount of light above the horizon is useful in limited
circumstances, for reading street signs. Anything else directed
upward is wasted, and will be seen only by folks in airplanes and
second or third story apartments. Good optics would take that excess
light and direct it more usefully, toward the road. This is the
second place where non-bike-specific beams fail. They send as much
light upward as downward. Tilting them lower to reduce upward losses
exacerbates the preceding problem.

The width of the brightest shaped beam needs to cover the path of the
cyclist, with enough illumination at enough distance that the cyclist
can react to any road hazards the beam shows. IMO, 8 feet wide at 30
feet is way plenty. I can easily pick out the two feet I really need
from that 8 feet that's illuminated. The "spill" light present in any
beam is plenty for conspicuity to the forward sides, as I mentioned
way above.

If you compare what I describe above to the beams from your current
car or motorcycle (assuming they're not antiques), you'll see that
what I described is what they've got, except that they have wider
beams. But wider beams have limited value for a bike, due primarily
to our slower speed and narrowness.

There is that one detail, though: When we turn slowly and sharply,
our bikes tilt as our handlebars turn. The tilt tends to throw the
headlight beam downward, rather than where we're going. If you don't
want to pivot the headlight (as on the Tucker automobile and some
modern copycats like BMW) or have auxiliary cornering lamps (as on
some luxury cars), bike headlight optics could be designed to throw
some light upward and to the sides. In effect, this would give a
smiley-shaped beam. It would light the way a bit better in tight,
slow speed turns, and it could be marketed as a safety feature to
those who believe motorists can't see a regular bike headlight.

Now compare what I've described with the beam from an MR bulb. That
beam is, by design, a symmetrical fog of light. Which is a better
match to the job at hand? Which has more engineering in its design?
Which one is really "poor" for a bike headlight?

- Frank Krygowski

On Jul 3, 11:00*pm, SMS wrote:

BTW, while low current indicator lamp type LEDs essentially last
forever, high current LEDs do indeed wear out (take a close look at an
LED traffic light some time), typically from heat related issues.

Mine are mounted on an Al piece of angle. I cannot feel any warmth in
it while riding at "normal" speeds (30 something kph). On the rollers
at 50kph on a cold night (little forced convection), the mounting
plate/heatsink was just warm to touch.

Excellent heat sinking through forced convection is very easy on a
bicycle.

JS.

On Jul 4, 12:41*pm, Frank Krygowski wrote:
On Jul 3, 7:04*pm, SMS wrote:

On 03/07/10 3:22 PM, James wrote:

snip

A wide beam angle has the
advantage of throwing light on the motorists waiting to pull out in
front of you, one of the most common hazards I face at night. *In my
particular circumstance, seeing the road is not an issue, being seen
by the motorists is.

I suppose circumstances may differ. *However, in my decades of night
riding, I've never had a motorist pull out in front of me, either from
a position waiting for a stop sign, or by making a left turn (here in
the US) from an oncoming position.

They must differ - I've had motorists slow and stop until I've just
got in "range" and then start to take off. At which point I've
already done the head checks and swung wide to avoid. IMO, the
brighter the light is in their face, the less likely they are of
driving out in front.

Now that more
lumens are easily available from a generator set's headlight, that
detail can be taken care of, if someone would design the proper LED
optic unit.*

I contacted a local designer/manufacturer recently. They replied but
seemed unconvinced that production of a dynamo powered LED head lamp
would be worth their while.

Modern headlights designed for generator lights have the best optics
on the bike market. *The beams are purposely designed to fit the
requirements of a road vehicle, to give even illumination of the road
surface, sufficient "throw" or light down the road, and sufficient
conspicuity for other road users to notice.

By contrast, MR bulbs are designed to evenly illuminate things like
overhead projectors, artwork displayed on walls, and kitchen
counters. *The requirements are NOT the same as those of a road
vehicle, and while they are fine for mountain biking, they do NOT do a
better job on the road.

I agree with what you said earlier, circumstances make for different
requirements.

* OK, let's talk optics again. *What would be the characteristics of
the ideal headlight beam?

What may be *ideal* for most is not necessarily ideal for all.

First, it's going to be very similar for either a bicycle, a
motorcycle and a car or truck, differing mostly in power. *There is no
need for the headlight of a 25 mph bicycle to be as powerful (in total
lumens) as that of a 75 mph car.

Low beam or high?

Again, I could ride my 60km after work route without a light at all if
I was the only vehicle on the road. The street lights are enough for
me to see the road, and I know off by heart where the holes are
anyway.

What I've found is that if my light is weak compared to a vehicle
light that is some distance behind me, my light is lost against theirs
as a motorist waiting in a side road to pull out is blinded by the
car's light and doesn't even see mine.

JS.

In article ,
SMS wrote:

I wanted to upgrade my existing incandescent dynamo light to a more
powerful light without spending a fortune.

I used a 4W MR16 lamp with 4 1W Cree Emitters. It's far better than the
incandescent lamp it replaced, and I suspect that it's comparable to
something like the IQ CYO or the SuperNova E3.

Probably not, but so what if it's good enough. Your reflector won't be
as correct for cycling, but if it puts enough light on the road for you
that's fine- as long as you're not blinding oncoming road users. And
for home brew builders, good cycling-specific optics are going to be
beyond almost all of us.

Cost was around $21.

That's very good indeed.

Project details and photos at: "http://nordicgroup.us/s78/mr16LED.htm"

Looks good; I liked the mounting system which looks sturdy but not
heavy, although I'd rig something up at fork crown height rather than
bar height because I prefer a lower beam. Good project, looks very
clean. That it is sealed against water is beneficial and it's nice to
have a "bump shield" around it. Congratulations!

I'd like to see a photo of the light in action especially the
illumination pattern, if you can do that. I've never tried that kind of
photography so I don't know what's involved.

--
That'll put marzipan in your pie plate, Bingo.

In article ,
SMS wrote:

I think cyclists are conditioned to expect a very narrow beam from
using the typical dynamo incandescent lamp which necessarily focuses
its very limited light narrowly onto a patch of road directly in
front of the bike.

You've never actually understood this issue, have you?

--
That'll put marzipan in your pie plate, Bingo.

In article
,
James wrote:

On Jul 4, 1:39*am, Frank Krygowski wrote:
On Jul 3, 9:00*am, SMS wrote:

On 03/07/10 5:02 AM, Peter Cole wrote:

I've replace some of my incandescent track lights with those,
but I have yet to see any with a narrow enough beam pattern for
a bike light.

If you want a narrow beam LED MR16 they are available.
Athttp://www.ledshoponline.com/ledlowvoltagebulbs.htmyoucan get
15, 25, 50, or 120 degree angles.
"http://www.dealextreme.com/details.dx/sku.33776" is said to have
about a 35 degree pattern from one user. I think the one I got is
about 50 degrees. I might order one of the narrower beams the
next time I place a DealExtreme order.

50 degrees is _awfully_ wide for a road vehicle headlight. *With a
radially symmetric beam like those Scharf insists on using, the
beam would be splashed wider than the road surface, and a similar
distance up and down, just a few feet forward of the bike. *It's
kind of like using a stick of dynamite when what you want is a
shotgun.

Not that that is always a bad thing, IMO. A wide beam angle has the
advantage of throwing light on the motorists waiting to pull out in
front of you, one of the most common hazards I face at night. In my
particular circumstance, seeing the road is not an issue, being seen
by the motorists is.

Blinding them with glare from poorly focused lamps, however, is not
helpful. It does not improve your safety at all and makes things more
unsafe for others.

To my observation I am much more obvious to drivers at night with my
headlights and taillights than I am in broad daylight. Being a bright
light source moving in a dark background increases one's "conspicuity."

--
That'll put marzipan in your pie plate, Bingo.

In article ,
SMS wrote:

On 03/07/10 3:22 PM, James wrote:

snip

A wide beam angle has the advantage of throwing light on the
motorists waiting to pull out in front of you, one of the most
common hazards I face at night. In my particular circumstance,
seeing the road is not an issue, being seen by the motorists is.

50 degrees is a bit wide. The problem is that most bicycle dynamo
lights are _far_ too narrow. This is by design because the limited
available light needs to be focused directly on the patch of road in
front of the bicycle, and they need to keep the cost down so the
optics are generally poor. The advent of higher power battery powered
lights with improved optics solved this problem, but dynamo lights
remained pretty poor until recently.

Nope, you *really* don't understand. Or you have really poor night
vision, I am not sure which.

--
That'll put marzipan in your pie plate, Bingo.

On 04/07/10 3:25 PM, James wrote:

They must differ - I've had motorists slow and stop until I've just
got in "range" and then start to take off. At which point I've
already done the head checks and swung wide to avoid. IMO, the
brighter the light is in their face, the less likely they are of
driving out in front.

Yes, definitely the case in my area. Especially vehicle turning left in
front of you if you don't have good lights. They associate a dim light
with a slow moving vehicle.

I was in a CVS yesterday (which used to be a Long's Drugs) and they
still had their bicycle parts section intact and they had two Bike Gear
12V dynamo sets left for $25 each. I may go back and get one and see how
well it works with the MR16.

I've noticed some things about the set-up I have now.

1. It doesn't get hot at all, since it's probably only at about 1/3 the
maximum power.

2. The finned heat sink allows light to show up through the fins, and
it's annoying, so there needs to be a shade over the top of the enclosure.

3. There is not much difference between low speed and high speed in
terms of the light. The dynamo saturates and that's the limit of it's
output no matter how fast you ride (which is why I'm thinking of trying
the 12V dynamo).

4. The beam pattern is very well shaped so the four LEDs are being
collimated into a good beam. If I ride in the center of the right lane
on a two lane road then the beam just reaches the sidewalk on the right
and shines into the opposing lane. This is a bit too wide of a beam. A
35 degree beam would be better than the present 50 degree beam or so.

On Jul 5, 3:30*pm, Tim McNamara wrote:
In article
,



*James wrote:
On Jul 4, 1:39 am, Frank Krygowski wrote:
On Jul 3, 9:00 am, SMS wrote:

On 03/07/10 5:02 AM, Peter Cole wrote:

I've replace some of my incandescent track lights with those,
but I have yet to see any with a narrow enough beam pattern for
a bike light.

If you want a narrow beam LED MR16 they are available.
Athttp://www.ledshoponline.com/ledlowvoltagebulbs.htmyoucanget
15, 25, 50, or 120 degree angles.
"http://www.dealextreme.com/details.dx/sku.33776" is said to have
about a 35 degree pattern from one user. I think the one I got is
about 50 degrees. I might order one of the narrower beams the
next time I place a DealExtreme order.

50 degrees is _awfully_ wide for a road vehicle headlight. With a
radially symmetric beam like those Scharf insists on using, the
beam would be splashed wider than the road surface, and a similar
distance up and down, just a few feet forward of the bike. It's
kind of like using a stick of dynamite when what you want is a
shotgun.

Not that that is always a bad thing, IMO. *A wide beam angle has the
advantage of throwing light on the motorists waiting to pull out in
front of you, one of the most common hazards I face at night. *In my
particular circumstance, seeing the road is not an issue, being seen
by the motorists is.

Blinding them with glare from poorly focused lamps, however, is not
helpful. *It does not improve your safety at all and makes things more
unsafe for others.

To my observation I am much more obvious to drivers at night with my
headlights and taillights than I am in broad daylight. Being a bright
light source moving in a dark background increases one's "conspicuity."

As I also tried to explain, it's easy to loose a weak light against a
backdrop of brighter ones. Sure, if you're the only vehicle on the
road, you're the brightest star in a dark sky, but that's rarely the
case I find.

If "blinding them with glare" is such a bad thing, why are modern
vehicles equipped with more blinding low beam lights than ever before?

Motorists very common mistake is underestimating my speed too. A weak
bicycle light doesn't help then either. A bold bright light is
something they can't ignore so easily, and even if they simply can't
determine what's blinding them until I've passed, that's a good thing
in my books.

So obviously a focused 1000lm in the drivers face is way over the top,
but compared with traditional bicycle lights, the 300-450lm I get is
comparable to a modern vehicle light, and once dispersed evenly across
the road in a wide pattern, gives adequate visibility, in my urban
jungle anyway.

JS.

On Jul 5, 5:38*pm, James wrote:


As I also tried to explain, it's easy to loose a weak light against a
backdrop of brighter ones. *

Are you _sure_? Specifically, with a practical bike headlight?

I ask because it seems you're making a statement based on your own
theory. But when I've done bike lighting tests with members of my
club, with friends or with family, any "real" bike headlights have
always been judged very noticeable. (I'm excepting the tiny coin-cell
units with one ordinary low-power LED.)

The same has been true when motorists and pedestrians have
spontaneously complimented my lights (like one about two months ago).
And it was certainly true when I was driving on a busy city street and
happened to see one of my utility cycling friends coming the other
way.

His choice of light, BTW, is an old Cateye halogen headlight powered
by two C batteries. It's certainly nothing exotic, and not nearly as
powerful as my generator light! Yet he was very noticeable in plenty
of time - at _least_ 1/4 mile away.

If "blinding them with glare" is such a bad thing, why are modern
vehicles equipped with more blinding low beam lights than ever before?

Why? Marketing, based on fear, "safety" and "damn the other guy."
It's the same marketing that sells SUVs.

So obviously a focused 1000lm in the drivers face is way over the top,
but compared with traditional bicycle lights, the 300-450lm I get is
comparable to a modern vehicle light, and once dispersed evenly across
the road in a wide pattern, gives adequate visibility, in my urban
jungle anyway.

Seriously, you should try something less blinding, and take the
elementary step of testing it out. Have a friend ride your bike for
you as you observe. It's an easy thing to do, and every one of the
many times I've ridden a friend's bike to show them, their conclusion
has been "Wow, my lights are a lot more visible than I thought." That
includes the most extreme "Safety!" campaigner of my bike club.

Incidentally, since SMS doesn't like the results, he claims that test
is completely invalid. However, I'm not aware of any data showing a
proper, legally lit nighttime cyclist is at any greater risk than a
proper daytime cyclist. If anyone has any data to the contrary, I'd
be interested.

- Frank Krygowski