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  #61  
Old March 8th 17, 06:20 PM posted to rec.bicycles.tech
Sepp Ruf
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jbeattie wrote:
On Monday, March 6, 2017 at 11:58:20 PM UTC-8, wrote:
On Tuesday, March 7, 2017 at 5:11:29 AM UTC+1, Frank Krygowski wrote:


http://peterwhitecycles.com/images/p...lux-II-800.jpg


That is the headlight I use and it looks exactly the same on a pitch dark
street.


I clearly have a defective hub or light or something -- or else I need a
pitch dark forest road with reflective gravel.


The hub is not likely to gradually fail. I've read much whining from you
about the bulbous Luxos B. Face it, whoever recommended it as a sole lamp
for rainy, high-traffic environments and twisty trails -- he was wrong.

Before dumping the Luxos altogether or converting it into a 3 amp LED host
fed by battery power, one could try a conservative lamp mod with a more
efficient LED that enhances output to 100 lux, as one guy claims,
http://laempie.de/?Fahrradlampen-Modifikation
But if your lamp really does 70 lux as it should, you might not be able to
appreciate the difference.

I couldn't see a godamn thing riding home last night -- again in a rain
storm, with a death grip on the bars because I was getting blown over. Wet
pavement swallows light, but the real problem is all the point-source
light pollution -- blinding car headlights when riding in wrong-side bike
facilities. I actually yelled at some guy on a bike with a mega-flasher.
Pop, pop, pop go the retinas. WTF? How could anyone possibly think that
was O.K.? This was in a wrong-side two-way bike facility, so I'm staring
into car lights on the left and bike lights on the right. Maybe I should
get some of those polarized night-driving glasses.


(See what you get when well-meaning activists demand special bike "facilities?")

What eyewear are you currently using in nightly traffic?
Years past last appointment at eye doc's?
Who would legitimately be selling "polarized night-driving" glasses? Don't
buy anything there!

Using 3000-3500K LEDs yourself, and blocking most of the enemy HID and LED
blue with light yellow tinted, AR-enhanced eyewear that blocks 450nm, but
passes 490nm, is a better plan. If you want to spend more for less effect,
consider getting the clear-looking Zeiss DriveSafe or similar glasses.

Ads
  #62  
Old March 8th 17, 06:22 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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On 3/8/2017 9:40 AM, jbeattie wrote:
On Monday, March 6, 2017 at 11:58:20 PM UTC-8, wrote:
On Tuesday, March 7, 2017 at 5:11:29 AM UTC+1, Frank Krygowski wrote:
On 3/6/2017 9:37 PM, sms wrote:

This light http://supernova-lights.com/en/supernova-e3-triple-2 claims
640 lumens at 4.5W. 4.5W is definitely possible from a nominal 3W
dynamo. It claims 800 lumens peak.

Note that his light, while sold in Germany, is not "road legal."
because, according to reviews, it doesn't suffer the problems of StVZO
lights, "It has a very broad light output that is closer to a floodlight
than a focused beam, and so doesn’t give the ‘tunnel’ effect of some of
the powerful battery-powered lights. This means it’s great for
illuminating branches and hazards above you and off to the side." As we
all know, the problem with StVZO legal lights are related to the
extremely focused spot beam.

Here's an example of an StVZO headlamp (2013 model) with the "extremely
focused spot beam" the Scharf complains about.
http://peterwhitecycles.com/images/p...lux-II-800.jpg

See that tiny spot? ;-)


--
- Frank Krygowski


That is the headlight I use and it looks exactly the same on a pitch dark street. So again I don't understand why people find this amount of light insufficient.


I clearly have a defective hub or light or something -- or else I need a pitch dark forest road with reflective gravel.

I couldn't see a godamn thing riding home last night -- again in a rain storm, with a death grip on the bars because I was getting blown over. Wet pavement swallows light, but the real problem is all the point-source light pollution -- blinding car headlights when riding in wrong-side bike facilities. I actually yelled at some guy on a bike with a mega-flasher. Pop, pop, pop go the retinas. WTF? How could anyone possibly think that was O.K.? This was in a wrong-side two-way bike facility, so I'm staring into car lights on the left and bike lights on the right. Maybe I should get some of those polarized night-driving glasses.


Two nights ago, I was driving home from a distant small town on a rainy
night. I noticed that, as I've mentioned, I couldn't really see my
car's headlight beams on the wet road. Instead, the road was visible
because its smooth wet surface reflected all the other light sources -
car headlights, car taillights, street lights, porch lights, etc.

I don't think there's any way to make a vehicle's headlight beams
prominent on such a wet smooth surface without scorching everyone else's
eyes.

It's like pointing a flashlight so it glances off a mirror. The surface
of a mirror doesn't light up; at best, if there's any dust on that
surface, you'll notice that. Grab a flashlight and try it.


--
- Frank Krygowski
  #63  
Old March 8th 17, 06:34 PM posted to rec.bicycles.tech
SMS
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On 3/6/2017 7:41 PM, Jeff Liebermann wrote:

I couldn't find any test reports or method used on the Supernova site.
I did find this test of the M99 model:
http://supernova-lights.com/en/blog/supernova-blog-1/post/first-test-performance-supernova-m99-pro-br-36
1100 lumens / 16 watts = 68.7 lumens/watt. Hmmm...


No need to use the most expensive LEDs on a battery powered light.

  #64  
Old March 8th 17, 06:39 PM posted to rec.bicycles.tech
SMS
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On 3/6/2017 6:27 PM, Jeff Liebermann wrote:
On Mon, 6 Mar 2017 10:47:34 -0800 (PST), wrote:

As a very occasional night rider I am interested in battery
powered lights but I think that I was attempting to give
a thought to a commuter that would use his light a great deal.


Do "occasional night riders" buy $150 headlights?

I notice that a large number of the people in our group
have flashing red rear lights and it isn't long before
these batteries run down enough that the taillight even
blinking is almost entirely unnoticeable. So I don't have
much respect for battery power for a great deal of use.


Well, that's one of the advantages of a dynamo. You never have to
worry about a dead or discharged battery or remember to carry a spare
dead or discharged battery. (Yes, I've done that).

I think you'll find a fair number of riders in your group using low
cost rear flashers like this:
http://www.ebay.com/itm/142066277090
$0.97 gets you a two AAA batteries packaged inside a flasher (postage
included). That's about the same price as the batteries, assuming
that they're alkaline and not carbon-zinc. One of my friends says
that he picks them out of the trash at the end of club rides because
people just toss them instead of trying to figure out how to pry open
the case and change the battery. It wouldn't do them much good even
if it was easy to open, because the COB (chip on board) electronics,
buried under a blob of epoxy, will self destruct if you touch, bend,
or push on it. As for not noticing a failure, most club riders will
inform your if they see a problem.


You used to be able to get 2xAA powered flashers, but they weren't 97

The best rear light was made by CatEye, and discontinued of course, but
still available via Amazon: https://www.amazon.com/dp/B00MQPEW10.
These ran for much much longer than AAA powered rear lights.

The trend now is toward smaller, USB rechargeable tail lights. No reason
you could not charge these via a dynamo.
  #65  
Old March 8th 17, 06:45 PM posted to rec.bicycles.tech
SMS
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On 3/6/2017 9:22 AM, Jeff Liebermann wrote:

Kinda looks like all of them will sorta deliver 2.5 watts before the
core saturates (to provide some level of voltage regulation). Further
down the page is a "Low Speed Power" graph, which shows that most can
produce 2.0-2.5 watts at 10km/hr. One could assume that the dynamo
will deliver 4.0 watts, but that would require buying one of the few
better (hub) dynamos listed, and riding at 25-30km/hr (15-19mph).

If I were designing or sizing a lighting system suitable for my slow
style of "cruising", I would use the worst case 10km/hr (6mph) and 2.0
watt figures.


You've touched on one of the reasons why dynamo lights haven't caught on
in the U.S..

I wish that it were possible for inexpensive, dynamo powered lights to
provide adequate illumination for commuting, but it isn't. I recognize
that few people can afford nearly $500 for a hub dynamo wheel and a
SuperNova E3 Triple 2. For commuting, where there is no problem
charging batteries every night, a high power LED set-up is more
economical and provides better illumination. It's hard enough getting
people to spend even $25 on a bicycle light, getting them fork out $500
for a dynamo wheel and a decent dynamo light would be damn near impossible.

  #66  
Old March 10th 17, 06:53 AM posted to rec.bicycles.tech
James[_8_]
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On 08/03/17 14:03, Sir Ridesalot wrote:
On Tuesday, March 7, 2017 at 7:09:21 PM UTC-5, James wrote: Snipped
If I was allowed to ride without a foam hat I could keep the sun
off my scalp with a cloth cap, but that's not an option in this
country.

If I develop a skin cancer on the top of my head, I shall seek to
sue the government, for their law makes adequate sun protection
with sufficient ventilation near on impossible.


Just curious, does the legislation specifically state that your
helmet must be worn on your head? Or does it simply state that a
helmet must be worn? On a long ride a few years ago it got extremely
hot so I slung mu helmet over my shoulder on a long srtrap. the
organizers at a rest stop saw it and said i must wear the helmet on
my head. I showed them the waiver and also showed them that it only
stated that I promised to wear a helmet but there was no mention of
wear I had to wear the helmet. Perhaps your local legislation has a
similar loophole?


"The rider of a bicycle must wear an approved bicycle helmet securely
fitted and fastened on the rider’s head, unless the rider is exempt from
wearing a bicycle helmet under another law of this jurisdiction."

I don't have an exemption.

--
JS
  #67  
Old March 10th 17, 06:55 AM posted to rec.bicycles.tech
James[_8_]
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On 09/03/17 00:35, Duane wrote:
On 07/03/2017 7:09 PM, James wrote:
snip
Now that you mention it...

I don't like putting sun screen on the top of my head because in the
heat and humidity I sweat a lot and it tends to run down into my eyes
and stings most painfully with sun screen mixed in.

So my foam hat has big ventilation holes that let the sun light through
to my scalp.

If I was allowed to ride without a foam hat I could keep the sun off my
scalp with a cloth cap, but that's not an option in this country.

If I develop a skin cancer on the top of my head, I shall seek to sue
the government, for their law makes adequate sun protection with
sufficient ventilation near on impossible.


When it's too hot to ride with my cycling cap under my helmet, I use one
of these:
https://www.mec.ca/en/product/5046-050/Summer-Skullcap

Probably a better idea than skin cancer.



How hot does it get where you are?

--
JS
  #68  
Old March 10th 17, 07:02 AM posted to rec.bicycles.tech
Sir Ridesalot
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On Friday, March 10, 2017 at 12:53:31 AM UTC-5, James wrote:
On 08/03/17 14:03, Sir Ridesalot wrote:
On Tuesday, March 7, 2017 at 7:09:21 PM UTC-5, James wrote: Snipped
If I was allowed to ride without a foam hat I could keep the sun
off my scalp with a cloth cap, but that's not an option in this
country.

If I develop a skin cancer on the top of my head, I shall seek to
sue the government, for their law makes adequate sun protection
with sufficient ventilation near on impossible.


Just curious, does the legislation specifically state that your
helmet must be worn on your head? Or does it simply state that a
helmet must be worn? On a long ride a few years ago it got extremely
hot so I slung mu helmet over my shoulder on a long srtrap. the
organizers at a rest stop saw it and said i must wear the helmet on
my head. I showed them the waiver and also showed them that it only
stated that I promised to wear a helmet but there was no mention of
wear I had to wear the helmet. Perhaps your local legislation has a
similar loophole?


"The rider of a bicycle must wear an approved bicycle helmet securely
fitted and fastened on the rider’s head, unless the rider is exempt from
wearing a bicycle helmet under another law of this jurisdiction."

I don't have an exemption.

--
JS



Bummer that your law is so specific.

Where I am in Ontario, Canada it can get in the 90s F and have a humidity index of 90 - 100% at times. That's hard on the system because you sweat a LOT but it doesn't evaporate but can run down into your eyes where it can burn as if it's an acid.

Cheers
  #69  
Old March 10th 17, 07:05 AM posted to rec.bicycles.tech
James[_8_]
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Posts: 5,771
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On 09/03/17 04:10, Frank Krygowski wrote:
On 3/8/2017 9:22 AM, jbeattie wrote:
On Tuesday, March 7, 2017 at 6:15:05 PM UTC-8, Frank Krygowski wrote:
On 3/6/2017 2:12 AM, DATAKOLL MARINE RESEARCH wrote:
Assumptions or measured ?

I forgot to respond to that question.

I've measured dynamo torque vs. speed. As James says, the resistance
torque of a dyno decreases as speed increases. It doesn't decrease as
much as speed increases, however, so the power required still increases
with speed.

Example: Soubitez roller dynamo

Speed (mph) 6 12 18 24
Torque (N*mm) 26.4 22.6 18.1 14.3 with 12 Ohm load
Torque (N*mm) 22.6 23.4 19.6 15.1 with 24 Ohm load

I found similar behavior with other dynamos.

With an open circuit, drive torque did increase with road speed.


Why would torque increase with speed with an open circuit?


I think because losses are inevitable. In addition to bearing drag,
there's a certain amount of loss due to eddy currents in the dynamo's
components, and there's windage loss churning the air around inside the
thing. Bottle dynamos spin at surprisingly high speed, BTW. 5000 rpm
would not be unusual.


It would be interesting to know for a hub dynamo over regular hub.
According to SP, about 1W at 30km/h with the light off. From previous
research into hubs with sealed bearings, I think I recall that each
bearing contributes about 0.5W at 50km/h, so about 0.6W at 30km/h for 2
bearings in a regular hub.

It's not like 0.4W is easy to detect by the rider.

--
JS
  #70  
Old March 10th 17, 07:12 AM posted to rec.bicycles.tech
James[_8_]
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On 10/03/17 17:02, Sir Ridesalot wrote:


Bummer that your law is so specific.

Where I am in Ontario, Canada it can get in the 90s F and have a
humidity index of 90 - 100% at times. That's hard on the system
because you sweat a LOT but it doesn't evaporate but can run down
into your eyes where it can burn as if it's an acid.

Cheers


We regularly get summertime temperatures over 100F here, and can be that
humid as well.

Good for rapid dehydration, hallucination, etc..

--
JS
 




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