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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. |
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#112
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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
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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
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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
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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/ |
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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
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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
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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
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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
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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 |
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