#61
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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. |
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#62
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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
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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. |
#65
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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
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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
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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
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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
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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
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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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