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lou.holtman 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 Still too much chroma, but a more realistic looking comparison than the aperiodical illumination of Mr. White's rustic driveway: http://baslerbikes.de/index.php/baslerbikes-2-Scheinwerfervergleich-2013-november.html That is the headlight I use and it looks exactly the same on a pitch dark street. Must be an extra-bright asphalt mix they use in NL - or simply a layer of sand. -- Merkel's new StVZO aiming instructions: crescent just below line H-H http://i.dailymail.co.uk/i/pix/2016/08/08/08/36FC213600000578-0-image-a-2_1470641631742.jpg |
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On 07/03/17 04:22, Jeff Liebermann wrote:
On Mon, 6 Mar 2017 17:04:13 +1100, James wrote: On 06/03/17 12:26, Jeff Liebermann wrote: Well, let's do some arithmetic. If your dynamo is rated at 3 watts, and your lighting is rated at 70 lumens/watt, then the most you can perhaps deliver is 210 lumens. 6 watts will get perhaps 420 lumens. Usually, it's less as the losses accumulate. Rectification losses, optical losses, heat degradation, and connector losses all conspire to produce lower output. We know that a 3W dynamo is quite capable of delivering more power than 3W, once the bicycle speed increases. 6W from a 3W dynamo is quite achievable, and the retardation torque drops off as speed increases too. Maybe: http://www.myra-simon.com/bike/dynotest.html See "Electrical Output" graph. 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. Back to electrical engineering school for you, Jeff. -- JS |
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On Tue, 07 Mar 2017 10:38:38 -0800, Jeff Liebermann
wrote: On Tue, 07 Mar 2017 20:00:47 +0700, John B. wrote: On Mon, 06 Mar 2017 20:10:21 -0800, Jeff Liebermann wrote: On Mon, 6 Mar 2017 16:57:41 +1100, James wrote: What if I don't want to play with batteries? Then play with calcium carbide (produces acetylene gas) instead: https://www.google.com/search?q=acetylene+bicycle+lamp&tbm=isch Ahem! I don't think you should suggest acetylene gas devices to some of the folks here. After all the safe limit for acetylene gas is 15 psi, above which it tends to go BOOM! :-) I once found a patent for an acetylene lantern design that used the heated gas pressure from the burning acetylene to pressurize a reed and thus act as a horn. I don't recall if it had a built in red tail light. What keeps an acetylene lantern from blowing up and ruining a ride is that the drip of water into the calcium carbide chamber is regulated by the back pressure produced by the reaction. No water means no gas is produced. It's a gravity fed affair, that's quite reliable and should never raise the internal pressure anywhere near 15 psig. Well, yes, that sounds like a very good idea, but.... Over here you can still buy an "acetylene generator" used to provide acetylene gas for a welding torch. These use the same system "no water, no gas" that the lamps do. But unfortunately over years of use they get rusty, dusty, corroded or just clogged up and every once in a while they do explode. Usually with loss of life. (but maybe if you wear a helmet and have a bright light... :-) The light isn't for me. It's for James who wants an alternative to changing batteries. I solved my lighting problem long ago: http://802.11junk.com/jeffl/pics/bicycles/slides/bicycle-flashlight.html :-} I solvd my problems using a much simpler solution... don't ride at night :-{ The big problem with an acetylene bicycle lantern is that a typical lantern only delivers about 30 to 50 lumens (my measurements). If you need a project, build an acetylene lamp that screws into an aluminum water bottle. http://www.4bobandbob.com/pages/pics/PremierDia.gif Don't need a project. But back when I was shooting on A.F. pistol teams we used "carbide lamps" to blacken the sights. Very simple lights with a canister for the carbide and a igniter incorporated in the reflector that you could flick with your thumb. Spit in the carbide receptacle, hold your hand over the reflector for a second or two and flick the igniter. POP (sometimes BANG) and you had a nice "rich" flame to blacken the sights. Quite a bright light too. I've used one to look for things in dark corners and they seem to give off sufficient light. Much better than my old Japanese bike with the bottle generator and the incandescent light bulb anyway. And, of course, you didn't have to pedal them to have lights :-) -- Cheers, John B. |
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On 07/03/17 06:15, jbeattie wrote:
On Sunday, March 5, 2017 at 9:57:44 PM UTC-8, James wrote: On 06/03/17 10:22, Barry Beams wrote: Burn time: What if you had five or ten hours battery time at your generator's brightness? My Oculus gives at least that much brightness, and a quickly field replaceable battery so you can put in a fresh battery. Other rechargeables leave you out of light and out of luck when the battery drains. Oculus also comes with a spare battery included. What if I don't want to play with batteries? Then you're done with the battery light discussion and may move on to helmets. 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. -- JS |
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On 07/03/17 11:50, Jeff Liebermann wrote:
On Mon, 6 Mar 2017 20:10:38 +0000 (UTC), David Scheidt wrote: Frank Krygowski wrote: :On Monday, March 6, 2017 at 1:37:23 PM UTC-5, AMuzi wrote: : I don't know about currents but 6V 4W bulbs for standard : dynamo systems have been around for twenty years and some : customers like them. I don't know if the dynamo drag is : noticeably greater. :6V 4W? I'm aware of 6V 3W bulbs, which are (or were) used mostly with bottle :dyno systems when driving a headlamp but no taillamp. They were an alternative :to 2.4 W in front and 0.6W in back. :I'm not aware of any common use of 6V 4W bulbs. It's a standard lantern size. http://www.rayovacindustrial.com/Products/Lights/Bulbs/K13-2TB-Krypton-Bulb-for-4D-Flashlights.aspx Ray-0-Vac K13-2TB. Made for 4D cell lanterns. 6v 3.6 watts. I couldn't find a 4 watt version. Most of what I found were 2.4 and 3.0 watt bulbs for bicycles. A 6V 3W dynamo will easily power a 12V 6W bulb, but at higher speed. In the same way, it has been tried and tested to install two 6V 3W headlights, and a switch that can bypass one light, or connect the two in series. -- JS |
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On 3/7/2017 3:42 PM, Sepp Ruf wrote:
lou.holtman 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 Still too much chroma, but a more realistic looking comparison than the aperiodical illumination of Mr. White's rustic driveway: http://baslerbikes.de/index.php/baslerbikes-2-Scheinwerfervergleich-2013-november.html That is the headlight I use and it looks exactly the same on a pitch dark street. Must be an extra-bright asphalt mix they use in NL - or simply a layer of sand. I've noticed that the asphalt does lighten in color somewhat as it ages. And I've noticed that dark road surfaces are not as visible in the headlight beam. This is true even with car headlight beams; the dark surface obviously reflects less light back to the operator's eyes. (That's probably covered in the definition of "dark.") This adds to the complexity of producing realistic screen shots of headlight beams. And it's already complex enough, because different camera exposure settings, different focal lengths, different lighting environments, etc. make one website's beam shots look quite different from another. Even if all testers used the same parameters, it might not match what the human eye perceives. If one were to develop an ASTM standard for headlight screen shots, all those and other factors would have to be uniformly controlled. Sounds like a good project for someone's masters' thesis. -- - Frank Krygowski |
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On 3/7/2017 7:09 PM, James wrote:
On 07/03/17 06:15, jbeattie wrote: On Sunday, March 5, 2017 at 9:57:44 PM UTC-8, James wrote: On 06/03/17 10:22, Barry Beams wrote: Burn time: What if you had five or ten hours battery time at your generator's brightness? My Oculus gives at least that much brightness, and a quickly field replaceable battery so you can put in a fresh battery. Other rechargeables leave you out of light and out of luck when the battery drains. Oculus also comes with a spare battery included. What if I don't want to play with batteries? Then you're done with the battery light discussion and may move on to helmets. 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. Now, now, now! This person in Melbourne https://pricetags.files.wordpress.co...bike.jpg?w=560 proves that it's a simple matter to have sun protection, yet to have the foam hat close enough to one's head for it's magic to be effective. ;-) BTW, I've seen the same trick used in America. So I've learned that any bike facility is a good bike facility, and a helmet anywhere near your head will save your life. -- - Frank Krygowski |
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On Tuesday, March 7, 2017 at 5:50:32 PM UTC-8, Frank Krygowski wrote:
On 3/7/2017 7:09 PM, James wrote: On 07/03/17 06:15, jbeattie wrote: On Sunday, March 5, 2017 at 9:57:44 PM UTC-8, James wrote: On 06/03/17 10:22, Barry Beams wrote: Burn time: What if you had five or ten hours battery time at your generator's brightness? My Oculus gives at least that much brightness, and a quickly field replaceable battery so you can put in a fresh battery. Other rechargeables leave you out of light and out of luck when the battery drains. Oculus also comes with a spare battery included. What if I don't want to play with batteries? Then you're done with the battery light discussion and may move on to helmets. 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. Now, now, now! This person in Melbourne https://pricetags.files.wordpress.co...bike.jpg?w=560 proves that it's a simple matter to have sun protection, yet to have the foam hat close enough to one's head for it's magic to be effective. ;-) BTW, I've seen the same trick used in America. So I've learned that any bike facility is a good bike facility, and a helmet anywhere near your head will save your life. http://www.aerotechdesigns.com/cycli...protector.html Reasonable accommodation for the hair-differently-abled. Not recommended for wearing in Kansas, Washington or any other US state where one could be mistaken for a Sikh. -- Jay Beattie. |
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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. -- - Frank Krygowski |
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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. -- JS 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? Cheers |
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On 3/7/2017 10:03 PM, 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. -- JS 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? Years ago, a friend and I drove support for a charity ride. The ride was not organized by our club, but our club volunteered to help out. Anyway, the ride had a "helmets required" policy. Late in the day, we came upon a guy, probably in his 60s, riding along with a rider number, but with his helmet strapped to his bike's back rack. He probably took it off because of the heat. My friend said "We've got to stop him and make him put his helmet on!" I said "How? Will we tell him he's not allowed to ride on this public road? Let him alone; he's old enough to know what he's doing." And I refused to slow or stop the car I was driving. BTW, that was so long ago, I still sort of believed in helmets back then. -- - Frank Krygowski |
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On Wed, 8 Mar 2017 11:09:16 +1100, James
wrote: On 07/03/17 06:15, jbeattie wrote: On Sunday, March 5, 2017 at 9:57:44 PM UTC-8, James wrote: On 06/03/17 10:22, Barry Beams wrote: Burn time: What if you had five or ten hours battery time at your generator's brightness? My Oculus gives at least that much brightness, and a quickly field replaceable battery so you can put in a fresh battery. Other rechargeables leave you out of light and out of luck when the battery drains. Oculus also comes with a spare battery included. What if I don't want to play with batteries? Then you're done with the battery light discussion and may move on to helmets. 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. Such a problem. You could use a "do rag", as they call it in America; or a Balaclava hood such as we have here, made of very stretchy fabric and can be worn as a skull cap or pulled down to shield the face and neck both worn under the helmet of course. See: http://tinyurl.com/hquplny And apparently a new innovation I see the ladies wearing this year. A sort of poke bonnet with at least a six inch deep brim. Again, of course, worn under the helmet and not only covering he crown of the head but keeps the face white also :-) Or perhaps that ultimate in protection for the Cyclist who is ultra worried about sun protection:: http://tinyurl.com/zf8uexq -- Cheers, John B. |
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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. |
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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? -- Jay Beattie. |
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On Monday, March 6, 2017 at 1:04:03 PM UTC-8, Doug Landau wrote:
What if I don't want to play with batteries? Then you're done with the battery light discussion and may move on to helmets. or carbon frames versus steel frames. Stainless!!! http://gearpatrol.com/2017/01/26/bes...l-bike-makers/ Can't do it. These people who are riding old rusty 6 speeds are telling me that carbon fiber is as safe as steel. |
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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. -- Jay Beattie. |
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On 08/03/2017 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. I hear your pain. I can't take these guys with they're freaking search beams on their bikes. Why is it not ok for cars to come up to you on a road with their high beams on but it's ok for a cyclist to blind everyone looking at them? And WTF is the point of high intensity (what you call mega) flashers at night? I've had near crashes due to both of these types of idiots. |
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On Wednesday, March 8, 2017 at 9:40:57 AM UTC-5, 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. -- Jay Beattie. What you need are flip up/flip down sunglass lenses to wear over glasses or clear cycling goggles. They do help a lot. I'd also like to be able to mount heat seeking missiles so that I could blow those blinding lights up. However I do realize that'd be illegal. Like I've mentioned before, there are times when i have to slam on my brakes becasue some idiot with super bright lights steady or strobe blinds me to the pointI can not see where the road or trail is and a stop is warranted lest I ride off either. Hmmm, I wonder if a good size flip up polycarbonate mirror on the front of my bike could/would reflect tht annoyingly dangerous over bright light back atthe rider using it? Letthem know what it's like to be blinded at night. Cheers |
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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. -- - Frank Krygowski |
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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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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 |
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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. |
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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. |
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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. |
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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 |
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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 |
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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 |
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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 |
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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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On Friday, March 10, 2017 at 1:12:14 AM UTC-5, James wrote:
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 Saw a guy one year on the organized ride here. After 100 kms he was at the ride end and was in agony from severe cramping. Ended up in ER and last I hear was he'd had 4 IV bags pumped into him. I've heard from professional medical personnel that severe cramping can actually pull ligaments or tendons away from the bones or muscles. Yopu really do not want to get that dehydrated. Cheers |
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On 10/03/2017 12:55 AM, James wrote:
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? Here in Quebec 32-34C. Not that bad as it isn't constant and not that humid. In New Orleans where I'm from, ~38 - 40C is not unusual. And always humid. I imagine it's hotter where you are but some of these UPF materials work pretty well. Light and cool. Not as spiffy as my cycling caps though. |
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On Monday, March 6, 2017 at 1:33:10 PM UTC-8, Joerg wrote:
On 2017-03-06 10:47, wrote: On Sunday, March 5, 2017 at 5:26:18 PM UTC-8, Jeff Liebermann wrote: On Sun, 5 Mar 2017 16:03:30 -0800 (PST), wrote: Thanks Jeff. These however all appear to be battery powered lights. We were sort of looking for lights that operated on the hub dynamo of 6V 3W or the Globe dynamo of 12V 6W or four times the power. Sorry, I thought you were still open to looking at battery powered lights. Here's what I fished out of my bookmark dumpster. No reviews and few tests, but some interesting dynamo graphs and numbers: http://www.myra-simon.com/bike/dynotest.html http://pilom.com/BicycleElectronics/DynamoCircuits.htm http://www.eeweb.com/blog/extreme_circuits/power-mosfet-bridge-rectifier This one is well worth reading (or skimming) and has quite a few test results: http://swhs.home.xs4all.nl/fiets/tests/verlichting/index_en.html This is why the hub generator has so little drag. Well, let's do some arithmetic. If your dynamo is rated at 3 watts, and your lighting is rated at 70 lumens/watt, then the most you can perhaps deliver is 210 lumens. 6 watts will get perhaps 420 lumens. Usually, it's less as the losses accumulate. Rectification losses, optical losses, heat degradation, and connector losses all conspire to produce lower output. You might find it useful to know how bright you want your light. For that, you'll need a Lux meter. I have a Lutron LX-102 which works nicely, and two junk meters I bought on eBay for sanity checks: http://www.ebay.com/sch/i.html?_nkw=lux+meter Get one that has a wide range. Lowest on mine is 1000 lux, and highest range is 50,000 lux. Find a dark night and an accomplice to operate the meter and send them down the road to the farthest distance that you might want to illuminate with your headlight. Use a headlight or flashlight to light up that area. Have your accompli's take a reading. It will probably be zero. Now, cut the distance in half and take a measurement. It will be 2x as bright (lux) at half the distance or 4x as bright at 1/4th the distance. Adjust the brightness for what it would have been if the light meter was sufficiently sensitive. Converting the brightness (lux) to luminous flux (lumens) requires that you know the distance to the accomplice, and the illumination angle. (1 lux = 1 lumen/square-meter) The form below makes a mess of bad assumptions but is good enough for a rough approximation: https://www.ledrise.com/shop_content.php?coID=19 Once you know how many lumens you think you need, and have adjusted for overly ambitious expectations, you can determine which lighting technology is suitable. Lets say you want to see 8 meters ahead and 20 degrees to each side (or 40 degree conical beamwidth) at 20 lux, which is rather dim. Plugging into the web page above, I get 485 lumens needed. You won't be able to do that with a 3w dynamo, but might squeeze by with a 6w and an oval shaped beam. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 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. I use my lights a great deal because they are on during the day as well except on segregated bike paths. Recharging is 2nd nature to me. Bike gets parked back in the garage, li'l round connector gets plugged in, done. Sometimes I deliberately do not charge past 8V until shortly before a ride. That improves battery lifetime. The real McCoy would be a worryfree system like in a car where it recharges while riding. If I ever switch the road bike front wheel to one with a hub dynamo I will do that. Right now it only has a bottle dynamo, too much drag and it eats the left side wall of "modern" tires. Power output of those is well above 3W at higher speeds if you provide the proper electronics. I could go into that but it's nerdy tech stuff. Essentially you need what is called a SEPIC or at least a buck converter plus some sort of maximum power point tracking (MPPT) control for that converter. Sounds more complicated than it really is but do not expect the bicycle industry to deliver anything even remotely close anytime soon.. Realistically you could eke out 4-6W depending on you speed. That's not enough to feed a MagicShine clone which wants 8W on high plus a watt or so for the rear lights. And maybe another 1-2W for the MP3 player. Plus the smart phone. And the electric razor :-) In my case this would work nicely because I need the full 10W total only on county roads and in city areas where car drivers tend to misbehave. Else it drops to a net load of 4-5W or even much lower. So the dynamo would recharge the watt-hours you used up on the county road. Once the battery gets full it throttles back. Just like in car. 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. Yep, that's a major nuisance. However ... one can power these lights off a regular 8.4V Li-Ion battery or even a dynamo (after rectification) by providing a 3V regulator. Small enough to fit where the two AAA cells used to be. If battery rear lights at least had a low-battery warning. Technically that would be a piece of cake. But no ... nothing :-( If you're riding a lot during the day with a DRL then you really should consider a dyno light. I was riding with my son this morning, and we passed a guy with a DRL, and I thought that it was unnecessarily bright for a DRL -- and goddamn if it wasn't a round-beam Supernova E3. The two of us were DRL-less, although I was personally in need of recharging. -- Jay Beattie. |
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On Wed, 8 Mar 2017 09:34:49 -0800, sms
wrote: 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. Yes, but they only deliver 68.7 lumens/watt instead of the spec sheet claim of 200 lumens/watt. As I explained in my previous rant, reflector loss, lens loss, electronics losses, power source ESR loss, and temperature derrating, are the culprits. In other words, don't expect to get spec sheet efficiencies from the finished product. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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On Wed, 8 Mar 2017 09:45:43 -0800, sms
wrote: 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.. Touched? I was trying to sledge hammer the reason. Basically, one design is not going to make everyone happy. Some riders can easily maintain the speeds necessary to utilize the dynamo at well above it's rated capacity. Others, like me, can barely make it spin. I'll spare you my rant on the benefits of a hybrid battery + dynamo system. 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. So how duz it cost to build one dynamo wheel and headlight? Prices are my guess(tm) based on experience and random googling. Shimano Nexus series hubs can be found for about $70. Wheelsmith spokes are about $0.50/ea or 26 for $18. Generic rim for $35. Tire, tube, and rim tape for $20. B&M Lumotec LUXOS B for $64. Wiring for free. ==================================== total = $207 While $207 is not cheap, it's much less than your $500 estimate. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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On Wed, 8 Mar 2017 09:39:28 -0800, sms
wrote: On 3/6/2017 6:27 PM, Jeff Liebermann wrote: http://www.ebay.com/itm/142066277090 $0.97 gets you a two AAA batteries packaged inside a flasher You used to be able to get 2xAA powered flashers, but they weren't 97¢ I haven't seen any with AA batteries in many years. All the cheap ones seems to AAA. The trend now is toward smaller, USB rechargeable tail lights. No reason you could not charge these via a dynamo. Yep. That would make it a hybrid battery + dynamo system, which is what methinks might be the best compromise. However, it won't work for megalumen headlights because the dynamo charger will not deliver enough power to fully recharge the large battery required to run high power lighting. Among the cheap tail lights a https://www.amazon.com/Solar-Powered-Bike-Tail-Light/dp/B006FC6CJA $2.78. However, I couldn't find any really cheap Li-Ion rechargeable tail lights. The best I could do is: http://www.ebay.com/itm/USB-Rechargeable-White-Red-Bicycle-Tail-Light-Waterproof-6Modes-COB-led-Tailight-/401141418710 for $8.50. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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On 3/10/2017 5:19 PM, Jeff Liebermann wrote:
On Wed, 8 Mar 2017 09:45:43 -0800, sms wrote: 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.. Touched? I was trying to sledge hammer the reason. Basically, one design is not going to make everyone happy. Some riders can easily maintain the speeds necessary to utilize the dynamo at well above it's rated capacity. Others, like me, can barely make it spin. I'll spare you my rant on the benefits of a hybrid battery + dynamo system. 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. So how duz it cost to build one dynamo wheel and headlight? Prices are my guess(tm) based on experience and random googling. Shimano Nexus series hubs can be found for about $70. Wheelsmith spokes are about $0.50/ea or 26 for $18. Generic rim for $35. Tire, tube, and rim tape for $20. B&M Lumotec LUXOS B for $64. Wiring for free. ==================================== total = $207 While $207 is not cheap, it's much less than your $500 estimate. Low price but no actual German electrons. You call that a fashion statement? -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
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On 3/10/2017 3:19 PM, Jeff Liebermann wrote:
On Wed, 8 Mar 2017 09:45:43 -0800, sms wrote: 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.. Touched? I was trying to sledge hammer the reason. Basically, one design is not going to make everyone happy. Some riders can easily maintain the speeds necessary to utilize the dynamo at well above it's rated capacity. Others, like me, can barely make it spin. I'll spare you my rant on the benefits of a hybrid battery + dynamo system. 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. So how duz it cost to build one dynamo wheel and headlight? Prices are my guess(tm) based on experience and random googling. Shimano Nexus series hubs can be found for about $70. Wheelsmith spokes are about $0.50/ea or 26 for $18. Generic rim for $35. Tire, tube, and rim tape for $20. B&M Lumotec LUXOS B for $64. Wiring for free. ==================================== total = $207 While $207 is not cheap, it's much less than your $500 estimate. Yes, I was looking at buying everything pre-made from a vendor like Peter White. A product, not a project. You can certainly buy a hub, spokes, and rim and assemble it yourself. You can even buy a good LED lamp for about $20, though without a standlight. You can buy dynamo wheels on e-Bay (generally NOS) for $100 or so, i.e. http://www.ebay.com/itm/282367087029 or http://www.ebay.com/itm/282316745203 plus shipping in some cases. |
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On 11/03/17 00:05, Duane wrote:
On 10/03/2017 12:55 AM, James wrote: 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? Here in Quebec 32-34C. Not that bad as it isn't constant and not that humid. In New Orleans where I'm from, ~38 - 40C is not unusual. And always humid. I imagine it's hotter where you are but some of these UPF materials work pretty well. Light and cool. Not as spiffy as my cycling caps though. Thanks. I might look in to it. Cheers. -- JS |
More About Lights
On Fri, 10 Mar 2017 17:30:57 -0600, AMuzi wrote:
So how duz it cost to build one dynamo wheel and headlight? Prices are my guess(tm) based on experience and random googling. Shimano Nexus series hubs can be found for about $70. Wheelsmith spokes are about $0.50/ea or 26 for $18. Typo. That should be 36 spokes for $18. Generic rim for $35. Tire, tube, and rim tape for $20. B&M Lumotec LUXOS B for $64. Wiring for free. ==================================== total = $207 While $207 is not cheap, it's much less than your $500 estimate. Low price but no actual German electrons. You call that a fashion statement? Well, Japanese and German electrons should be compatible. However, the cost of the SON hub needed to produce genuine German electrons is well over $200. That brings the cost of the wheel to $337. The prices I picked out of thin air are the cheapest that I could find new from vendors that sell component parts. I specifically did not use Banggood and AliExpress to avoid counterfeits and junk. Modifying an existing front wheel would save $55 for the rim, tire, and tube. Even running on Japanese electrons, it's still a rather expensive solution compared to a battery powered headlight and goes a long way to explain why battery powered lights are more common. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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