A Cycling & bikes forum. CycleBanter.com

Go Back   Home » CycleBanter.com forum » rec.bicycles » Techniques
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

More About Lights



 
 
Thread Tools Display Modes
  #111  
Old March 14th 17, 03:14 AM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 5,697
Default More About Lights

On Mon, 13 Mar 2017 15:19:22 -0400, Frank Krygowski
wrote:

On 3/13/2017 2:06 PM, Joerg wrote:

Then you'd be back to this inferior dynamo lighting which goes out at
the traffic light, or uses dimmed or short-lived light if there is a
supercap installed.


Where are the tragic tales of cyclists who are seriously injured or
killed because their dynamo standlights were too dim or too short-lived?
Somehow those tales have failed to make it into the safety literature!


But what you don't understand is that, with the horrendous number of
bicycle deaths annually, it might make a difference.

After all there were 818 bicycle deaths in 2015 and Statista tells us
that there were some 67 million bicyclists in the same era. That is a
death rate of 0.0012209%, or to put it another way approximately one
cyclist died out of each 82 thousand cyclists.

In contrast, it might be noted that infant morality is 1 in 173 live
births.

Just think, with proper lighting (and helmets) all those people might
have lived.
--
Cheers,

John B.

Ads
  #112  
Old March 14th 17, 03:49 AM posted to rec.bicycles.tech
JBeattie
external usenet poster
 
Posts: 5,870
Default More About Lights

On Monday, March 13, 2017 at 5:36:49 PM UTC-7, Frank Krygowski wrote:
On 3/13/2017 4:08 PM, sms wrote:
On 3/13/2017 12:50 PM, Joerg wrote:
On 2017-03-13 12:19, Frank Krygowski wrote:
On 3/13/2017 2:06 PM, Joerg wrote:

Then you'd be back to this inferior dynamo lighting which goes out at
the traffic light, or uses dimmed or short-lived light if there is a
supercap installed.

Where are the tragic tales of cyclists who are seriously injured or
killed because their dynamo standlights were too dim or too short-lived?
Somehow those tales have failed to make it into the safety literature!


As we all know reports of fatal car-cyclist collisions are notoriously
short on details.

You claim to be something like a "teacher for safe cycling" yet you
don't know or ignore the most basic safety precautions. Astounding.
Actually, sad.


Unless their is a case-controlled, double-blind, study, Frank won't
believe that increasing visibility at night, both for seeing and being
seen, is beneficial.


Oh, come on, Stephen. People getting hit because their standlights are
too dim? We don't even have anecdotes about that!


As close as I can get to an anecdote is the guy I saw a night or two ago here in SLC who was mostly invisible until his dyno light lit up. It didn't have any stand light. He was turning across traffic, and I didn't hit him -- but a little more warning would have been nice.

-- Jay Beattie.
  #113  
Old March 14th 17, 04:00 AM posted to rec.bicycles.tech
Jeff Liebermann
external usenet poster
 
Posts: 4,018
Default More About Lights

On Mon, 13 Mar 2017 12:38:07 -0700, Joerg
wrote:

However, in your link they say, quote "Hubs don't go into saturation
easily so that at moderate to high speed, they develop a higher voltage
than bottle dynamos, assuming they are not loaded with the typical 6 V /
3 W lights. To see whats possible, I ran a Shimano DH-3D71 at 136 km/h
in a test stand. The voltage generated was sufficient to ignite a
fluorescent tube and subsequently drive it at 55 V and 500 mA".

55V at 500mA. This is encouraging.


That's 27.5 watts out of a 3 watt dynamo. I was impressed, until I
converted 136 km/hr and found that it was 84.5 mph. With a rocket
assisted bicycle, I might be able to do that.

The author is mostly correct about hubs not going into saturation as
easily and bottle dynamos. However, they do go into staturation, just
at a higher RPM.

I could make 12V filament lighting glow like halogen at high speed.


I don't know anyone that regularly rides at 136 km/hr (84.5 mph). My
average riding speed is probably a leisurely 15 km/hr (9 mph).

It's best to try that out on the bench, using a rechargeable drill and such.


I was thinking of building a benchtop dynamometer sized for bicycle
lighting. I don't have the equipment to calibrate it so I could
measure overall efficiency, but certainly can make comparative
measurements of the input power(s) required to light an oversized load
or bulb. Basically, just a DC motor with a DC wattmeter on the power
leads.
http://www.ebay.com/itm/122373782338
(Yet another project that I'll never finish).

[1] SON dynamo driving MOSFET bridge:
https://www.flickr.com/photos/kurtsj00/8480800746/in/photostream
http://www.candlepowerforums.com/vb/showthread.php?355392-Spice-code-for-dynamo-output


"CPF is currently closed for maintenance".


They were down most of the morning but are now back up. No info about
what happened.



--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #114  
Old March 14th 17, 06:10 AM posted to rec.bicycles.tech
John B.[_3_]
external usenet poster
 
Posts: 5,697
Default More About Lights

On Mon, 13 Mar 2017 20:36:44 -0400, Frank Krygowski
wrote:

On 3/13/2017 4:08 PM, sms wrote:
On 3/13/2017 12:50 PM, Joerg wrote:
On 2017-03-13 12:19, Frank Krygowski wrote:
On 3/13/2017 2:06 PM, Joerg wrote:

Then you'd be back to this inferior dynamo lighting which goes out at
the traffic light, or uses dimmed or short-lived light if there is a
supercap installed.

Where are the tragic tales of cyclists who are seriously injured or
killed because their dynamo standlights were too dim or too short-lived?
Somehow those tales have failed to make it into the safety literature!


As we all know reports of fatal car-cyclist collisions are notoriously
short on details.

You claim to be something like a "teacher for safe cycling" yet you
don't know or ignore the most basic safety precautions. Astounding.
Actually, sad.


Unless their is a case-controlled, double-blind, study, Frank won't
believe that increasing visibility at night, both for seeing and being
seen, is beneficial.


Oh, come on, Stephen. People getting hit because their standlights are
too dim? We don't even have anecdotes about that!


Just wait for a moment or two :-)
--
Cheers,

John B.

  #115  
Old March 14th 17, 03:41 PM posted to rec.bicycles.tech
Joerg[_2_]
external usenet poster
 
Posts: 6,016
Default More About Lights

On 2017-03-13 17:19, Sir Ridesalot wrote:
On Monday, March 13, 2017 at 2:09:05 PM UTC-4, Joerg wrote:
On 2017-03-12 15:21, James wrote:
On 13/03/17 01:57, Joerg wrote:
On 2017-03-11 16:28, Sir Ridesalot wrote:


You need to look again at more modern stuff because many dynamo
hub standlights are quite bright for the time they stay on usually
a ferw minutes or so if needed. But then again absolutely NOTHING
ever works for you off the shelf.


Wrong, it does and I have written about it here in the NG. I bought
a Cree XM-L based light each for the road bike and the MTB. Of
course, since almost nothing in the world of cycling is very robust
or complete this had to be spiced up. Both lights got diffusor lenses
because they will otherwise blind others and the light distribution
wasn't to my liking. Big deal, you just buy diffusor lenses and
install them. Then the battery holders are lousy. This took a little
more work but nothing that can't be done with a trip to the hardware
store and basic hand tools:

http://www.analogconsultants.com/ng/bike/Battbox2.JPG


You just proved Sir's point. Well done Joerg.


Huh? I made it quite clear that my solution works. It does very well.

--
Regards, Joerg

http://www.analogconsultants.com/


Because NOTHING works for you umn.ess you modify it.


Not true. As I said before the lights on the MTB and the road bike are
standard off the shelf. The diffusor lenses I installed were also off
the shelf. Swapping the plain plastic against those is not something
that qualifies as "work" because it merely involved screwing off a ring
and then screwing that back on. Like putting relish on a sausage which
doesn't alter the sausage.

The new WTB saddle is also unmodified. And the panniers. And the
speedometers. And ...

Yes, a lot of cycling gear is designed wrong or built in an inferior
quality but not everything. Therefore, your statement "absolutely
NOTHING" is not correct :-)

--
Regards, Joerg

http://www.analogconsultants.com/
  #116  
Old March 14th 17, 03:41 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
external usenet poster
 
Posts: 10,538
Default More About Lights

On 3/13/2017 10:49 PM, jbeattie wrote:
On Monday, March 13, 2017 at 5:36:49 PM UTC-7, Frank Krygowski wrote:

Oh, come on, Stephen. People getting hit because their standlights are
too dim? We don't even have anecdotes about that!


As close as I can get to an anecdote is the guy I saw a night or two ago here in SLC who was mostly invisible until his dyno light lit up. It didn't have any stand light. He was turning across traffic, and I didn't hit him -- but a little more warning would have been nice.


Thinking about traffic situations, the main ones that might harm a
stationary cyclist with no standlights may be these:

Cyclist waiting to turn left in a normal traffic lane, where the danger
is being hit from behind. (The danger's about nil in a left-turn-only
lane.)

And a cyclist (say, facing north) waiting first in line at a red light
or stop sign, when a motorist coming from the east extremely cuts the
corner to turn south.

But AFAIK, detailed crash studies (for example, the Cross-Fisher study
or the Tan study) don't identify those situations as causing crashes.
Such crashes must be very rare.

It's likely that simple reflectors are sufficient protection in those
cases. In fact, in another (um, more serious?) forum, when some
well-known bike advocates were ridiculing the CPSC requirements for side
reflectors, I pointed out that the second situation above was one
justification for side reflectors.

Reflectors can be as bright as most lights, provided they're clean and
properly oriented. I've mentioned this before, but one time a friend
drove past me at night, then stopped his car to ask me "What's that
super bright light down low on the back of your bike?"

t was actually a red reflector mounted at about axle height.

And reflectors weigh less than lights! ;-)

--
- Frank Krygowski
  #117  
Old March 14th 17, 03:46 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
external usenet poster
 
Posts: 10,538
Default More About Lights

On 3/13/2017 11:00 PM, Jeff Liebermann wrote:
On Mon, 13 Mar 2017 12:38:07 -0700, Joerg
wrote:

However, in your link they say, quote "Hubs don't go into saturation
easily so that at moderate to high speed, they develop a higher voltage
than bottle dynamos, assuming they are not loaded with the typical 6 V /
3 W lights. To see whats possible, I ran a Shimano DH-3D71 at 136 km/h
in a test stand. The voltage generated was sufficient to ignite a
fluorescent tube and subsequently drive it at 55 V and 500 mA".

55V at 500mA. This is encouraging.


That's 27.5 watts out of a 3 watt dynamo. I was impressed, until I
converted 136 km/hr and found that it was 84.5 mph. With a rocket
assisted bicycle, I might be able to do that.

The author is mostly correct about hubs not going into saturation as
easily and bottle dynamos. However, they do go into staturation, just
at a higher RPM.

I could make 12V filament lighting glow like halogen at high speed.


I don't know anyone that regularly rides at 136 km/hr (84.5 mph). My
average riding speed is probably a leisurely 15 km/hr (9 mph).

It's best to try that out on the bench, using a rechargeable drill and such.


I was thinking of building a benchtop dynamometer sized for bicycle
lighting. I don't have the equipment to calibrate it so I could
measure overall efficiency, but certainly can make comparative
measurements of the input power(s) required to light an oversized load
or bulb. Basically, just a DC motor with a DC wattmeter on the power
leads.
http://www.ebay.com/itm/122373782338
(Yet another project that I'll never finish).


What are you intending to measure? Input power to a bike dynamo?



--
- Frank Krygowski
  #118  
Old March 14th 17, 03:54 PM posted to rec.bicycles.tech
Joerg[_2_]
external usenet poster
 
Posts: 6,016
Default More About Lights

On 2017-03-13 20:00, Jeff Liebermann wrote:
On Mon, 13 Mar 2017 12:38:07 -0700, Joerg
wrote:

However, in your link they say, quote "Hubs don't go into saturation
easily so that at moderate to high speed, they develop a higher voltage
than bottle dynamos, assuming they are not loaded with the typical 6 V /
3 W lights. To see whats possible, I ran a Shimano DH-3D71 at 136 km/h
in a test stand. The voltage generated was sufficient to ignite a
fluorescent tube and subsequently drive it at 55 V and 500 mA".

55V at 500mA. This is encouraging.


That's 27.5 watts out of a 3 watt dynamo. I was impressed, until I
converted 136 km/hr and found that it was 84.5 mph. With a rocket
assisted bicycle, I might be able to do that.


Well, yeah, they just wanted to see where the limit is. I guess the
enameled copper wire inside would smoke out if you kept that speed for long.

However, this means I should be comfortably able to milk 10W or more out
of such a dynamo on a long downhill stretch and maybe north of 5W during
regular rides on flat terrain. IOW there seems to be nothing that
inherently limits things to the usual measly 3-4W.


The author is mostly correct about hubs not going into saturation as
easily and bottle dynamos. However, they do go into staturation, just
at a higher RPM.


If that happens above 84mph I shall be happy :-)


I could make 12V filament lighting glow like halogen at high speed.


I don't know anyone that regularly rides at 136 km/hr (84.5 mph). My
average riding speed is probably a leisurely 15 km/hr (9 mph).


My usual speed in the valley is 15-20mph but the average drops to
11-12mph here in the hills, in part because you can't always safely bomb
down a downhill section. A friend keeps it at 25mph all the way to
Folsom Lake, about 45mins. I did that exactly once following him and I
thought I'd fall out of the saddle when we arrived. Too old for that.
The embarrassing fact though is that he is slightly older.


It's best to try that out on the bench, using a rechargeable drill and such.


I was thinking of building a benchtop dynamometer sized for bicycle
lighting. I don't have the equipment to calibrate it so I could
measure overall efficiency, but certainly can make comparative
measurements of the input power(s) required to light an oversized load
or bulb. Basically, just a DC motor with a DC wattmeter on the power
leads.
http://www.ebay.com/itm/122373782338
(Yet another project that I'll never finish).


That is a neat little instrument.


[1] SON dynamo driving MOSFET bridge:
https://www.flickr.com/photos/kurtsj00/8480800746/in/photostream
http://www.candlepowerforums.com/vb/showthread.php?355392-Spice-code-for-dynamo-output


"CPF is currently closed for maintenance".


They were down most of the morning but are now back up. No info about
what happened.


There almost never is. Still slow in response time. Anyhow, I don't
think a dynamo can easily be simulated until you start with a mechanical
model of it and that gets into COMSOL and other really expensive
modeling software. Maybe possible with MathCad which I have but rarely
use so I became rusty there.

--
Regards, Joerg

http://www.analogconsultants.com/
  #119  
Old March 14th 17, 04:32 PM posted to rec.bicycles.tech
Sir Ridesalot
external usenet poster
 
Posts: 5,270
Default More About Lights

On Tuesday, March 14, 2017 at 10:41:18 AM UTC-4, Frank Krygowski wrote:
On 3/13/2017 10:49 PM, jbeattie wrote:
On Monday, March 13, 2017 at 5:36:49 PM UTC-7, Frank Krygowski wrote:

Oh, come on, Stephen. People getting hit because their standlights are
too dim? We don't even have anecdotes about that!


As close as I can get to an anecdote is the guy I saw a night or two ago here in SLC who was mostly invisible until his dyno light lit up. It didn't have any stand light. He was turning across traffic, and I didn't hit him -- but a little more warning would have been nice.


Thinking about traffic situations, the main ones that might harm a
stationary cyclist with no standlights may be these:

Cyclist waiting to turn left in a normal traffic lane, where the danger
is being hit from behind. (The danger's about nil in a left-turn-only
lane.)

And a cyclist (say, facing north) waiting first in line at a red light
or stop sign, when a motorist coming from the east extremely cuts the
corner to turn south.

But AFAIK, detailed crash studies (for example, the Cross-Fisher study
or the Tan study) don't identify those situations as causing crashes.
Such crashes must be very rare.

It's likely that simple reflectors are sufficient protection in those
cases. In fact, in another (um, more serious?) forum, when some
well-known bike advocates were ridiculing the CPSC requirements for side
reflectors, I pointed out that the second situation above was one
justification for side reflectors.

Reflectors can be as bright as most lights, provided they're clean and
properly oriented. I've mentioned this before, but one time a friend
drove past me at night, then stopped his car to ask me "What's that
super bright light down low on the back of your bike?"

t was actually a red reflector mounted at about axle height.

And reflectors weigh less than lights! ;-)

--
- Frank Krygowski


Cycle Sense: Why Reflectors Don't Work

There are optical reasons for all those crashes and deaths

by John Schubert

http://sheldonbrown.com/reflectors.html
  #120  
Old March 14th 17, 05:09 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
external usenet poster
 
Posts: 10,538
Default More About Lights

On 3/14/2017 11:32 AM, Sir Ridesalot wrote:
On Tuesday, March 14, 2017 at 10:41:18 AM UTC-4, Frank Krygowski wrote:
On 3/13/2017 10:49 PM, jbeattie wrote:
On Monday, March 13, 2017 at 5:36:49 PM UTC-7, Frank Krygowski wrote:

Oh, come on, Stephen. People getting hit because their standlights are
too dim? We don't even have anecdotes about that!

As close as I can get to an anecdote is the guy I saw a night or two ago here in SLC who was mostly invisible until his dyno light lit up. It didn't have any stand light. He was turning across traffic, and I didn't hit him -- but a little more warning would have been nice.


Thinking about traffic situations, the main ones that might harm a
stationary cyclist with no standlights may be these:

Cyclist waiting to turn left in a normal traffic lane, where the danger
is being hit from behind. (The danger's about nil in a left-turn-only
lane.)

And a cyclist (say, facing north) waiting first in line at a red light
or stop sign, when a motorist coming from the east extremely cuts the
corner to turn south.

But AFAIK, detailed crash studies (for example, the Cross-Fisher study
or the Tan study) don't identify those situations as causing crashes.
Such crashes must be very rare.

It's likely that simple reflectors are sufficient protection in those
cases. In fact, in another (um, more serious?) forum, when some
well-known bike advocates were ridiculing the CPSC requirements for side
reflectors, I pointed out that the second situation above was one
justification for side reflectors.

Reflectors can be as bright as most lights, provided they're clean and
properly oriented. I've mentioned this before, but one time a friend
drove past me at night, then stopped his car to ask me "What's that
super bright light down low on the back of your bike?"

t was actually a red reflector mounted at about axle height.

And reflectors weigh less than lights! ;-)

--
- Frank Krygowski


Cycle Sense: Why Reflectors Don't Work

There are optical reasons for all those crashes and deaths

by John Schubert

http://sheldonbrown.com/reflectors.html


Schubert was one of the guys in on the discussion I mentioned earlier.
In fact, when I pointed out the second situation above (a left turning
car cutting the corner), he was the one who said "Frank's done a good
job of identifying a benefit of a side reflector."

To be clear: I do advocate using a taillight. Ohio law requires one
anyway. But by my observations and those of my club mates, an ancient
and inexpensive AA blinky is sufficient. (Yes, we have tested this.)

I also have either reflectors or reflective tape on most bikes. It's
true that there are limits on reflector efficacy; but it's not difficult
to keep them clean and keep them well-aimed. (BTW, the caution about
crooked reflectors applies just as much to taillights. It's common to
see them pointed at the worms or the airliners.)

But the point I was discussing was whether too brief or too dim
standlights really kill or seriously injure _stationary_ bicyclists.
I've never heard of such a case. I think it's yet another exaggerated
danger.


--
- Frank Krygowski
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Dynamo Lights viz Battery Lights in snow qand slush? Sir Ridesalot Techniques 6 March 4th 15 11:36 PM
No lights, dark clothing, no reflectives, no street lights. Mrcheerful UK 153 November 4th 14 10:19 AM
Maybe it's safer to run red lights than to wait for green lights. SMS General 16 September 24th 08 09:51 PM
Light Theft (solutions — small pocket lights, or heavy duty well secured lights?) David Johnson UK 24 August 29th 07 02:32 PM
Break lights turn lights and handle bar lights Truepurple Techniques 30 November 17th 03 05:02 AM


All times are GMT +1. The time now is 01:31 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 CycleBanter.com.
The comments are property of their posters.