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#71
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Is there an updated Dynotest somewhere?
On 9/16/2017 10:51 AM, Joerg wrote:
On a steep uphill I sure want my rear light as bright as it gets. On winding uphill stretches the risk of being seen too late is highest. Have you ever bothered to get a friend to ride your bike at night, then observe your bike's lights and reflectors as you drove your car? I've done things like that many times, with my family, with friends, with bike club members. And as mentioned, I've gotten spontaneous compliments from motorists. All of this testing has showed that a cyclist does NOT need super-bright lights or high tech equipment to be perfectly visible. The modern paranoia calling for super-bright lights is silly. It's spouted by people who haven't done simple tests. -- - Frank Krygowski |
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#72
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Is there an updated Dynotest somewhere?
Frank Krygowski writes:
On 9/14/2017 4:43 PM, Radey Shouman wrote: Frank Krygowski writes: On 9/14/2017 10:26 AM, Ralph Barone wrote: bob prohaska wrote: Sepp Ruf wrote: For Rob who might experience mental drag uphill from just having to see a big, heavy, non-laminated hub slowly revolving in the front wheel, the smallish Shimano DH-T780-1N, 1.5W 250mA class, might suffice[1] once he grows sick of the Soubitez. Best price I see is 96 euros a pair from CNC Hamburg on ebay, no overseas shipping available, though. http://www.ebay.com/itm/253093811841 [1] DRL does not require more than 100 lumens if you get the optics right. It's a bit puzzling how folks seem to excuse poor design in dynamo hubs when they're considerably more fanatic about optimizing every other part of a bicycle. In particular, the 3 watt standard is utterly archaic. Folks now are starting to use dynamos to power electronics, and I suspect most would opt for more than 3 watt lights if useful designs were available. I still don't understand why high-end builders like Schmidt don't use salient-pole armatures, which could be constructed from standard motor laminations (instead of the custom clawpole monolith used now). That would shorten the iron path dramatically, reducing reluctance, reduce the length of copper, reducing resistance. The performance gains can be traded for lighter weight, higher efficiency or higher power. Every motor builder in the world does it that way, why not dyamo hub builders? Maybe there _is_ a technical reason, but it certainly isn't apparent to me. The use of incandescent bulbs may have set the tradition, but it's certainly no reason to continue. At this rate I won't "get sick" of the Soubitez, I'll wear it out. bob prohaska Machine theory is a bit of a black art for me, but I suspect that the "less optimized" magnetics in hub dynamos provides the extra leakage inductance required to make it self regulate into a 12 ohm load. I fully agree that a less well regulated output plus a switching regulator could work very well with modern electronics. Is it feasible to use a switching regulator when you've got as much inductance as a typical hub dynamo? I'd have thought that causes problems. Happens all the time. Google "h-bridge", and notice all those diodes in parallel with the switching components, allowing current always to continue to circulate through some path. Typically the diodes are in the same package as the switching component, eg MOSFET. So spikes, etc. from switching inductors get to sort of bleed off through diodes? Is that the idea? Again, electronics isn't my thing. Roughly speaking, if you give a current across an inductor a reasonable path to follow, voltage will not spike until it finds an unreasonable path. I am familiar (OJT, not education) with the control of motors by switching amplifiers. During a large part of a typical cycle, when PWM is "off", currents actually circulate either through the high voltage or ground bus, slowly wasting power but doing no spectacular harm. The diodes are to provide a path, from ground to high voltage, during PWM dead time. I'm not personally familar with algorithms for controlling dynamos, but know that with motors in regeneration (braking), it is sometimes necessary to provide an alternate current path that dissipates power, in order to prevent unwanted voltage rise. It seems to me that controlling a permanent magnet dyanamo at part load is probably harder than some here think it is. Automotive and larger dynamos are normally controlled by varying the current through the field windings, an option that is not available for bicycles. My guess is that claw pole armatures, with their self regulation by magnetic saturation, are actually a good practical solution. Bicycle lighting systems must operate usefully at low speed, and usually can't do anything useful with several times the power at high speed. -- |
#73
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Is there an updated Dynotest somewhere?
On 2017-09-16 09:16, Frank Krygowski wrote:
On 9/16/2017 10:34 AM, Joerg wrote: No, cyclists get run over. Doesn't matter whether hill or not. A vehicle that travels at 1/4 the speed of motorized traffic or less is always at higher risk in the lane than traffic going at same speed. The risk goes up as the speed goes down. More bull****, Joerg, or at least, more ignorance of data. Motorcyclists have a fatality per hour rate roughly 30 times higher than bicyclists. You can't say that risk goes up as speed goes down. As an engineer you should at least try to find the real reasons. They can be summed up in videos like this: https://www.youtube.com/watch?v=cjtjexSg0SM -- Regards, Joerg http://www.analogconsultants.com/ |
#74
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Is there an updated Dynotest somewhere?
On 2017-09-16 09:24, Frank Krygowski wrote:
On 9/16/2017 10:46 AM, Joerg wrote: No matter, Frank can lament all day long, I know for a fact that since I have bright lights front and back the number of close calls has substantially dropped. So as far as lighting is concerned, mission accomplished. And I can say precisely the same thing about my learning to ride more toward lane center, instead of at the road edge. I suppose if you are terrified enough to hide near the gutter, you may have a lot of close calls. That's pretty common. And I suppose glaring bright lights might reduce those gutter-induced close calls a bit. But riding more prominently as permitted by law does more, even though you refuse to understand this. See http://cyclingsavvy.org/2011/05/i-am-no-road-warrior/ and https://www.youtube.com/watch?v=yu5V...ature=youtu.be Piece of cake. On lane this narrow I also do that. Now try it on a 55mph county road. Aside from all the hairy situations you'll soon get pulled over by Highway Patrol and later pay a painful three-digit fine. -- Regards, Joerg http://www.analogconsultants.com/ |
#75
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Is there an updated Dynotest somewhere?
On 2017-09-16 09:28, Frank Krygowski wrote:
On 9/16/2017 10:51 AM, Joerg wrote: On a steep uphill I sure want my rear light as bright as it gets. On winding uphill stretches the risk of being seen too late is highest. Have you ever bothered to get a friend to ride your bike at night, then observe your bike's lights and reflectors as you drove your car? I've done things like that many times, with my family, with friends, with bike club members. And as mentioned, I've gotten spontaneous compliments from motorists. All of this testing has showed that a cyclist does NOT need super-bright lights or high tech equipment to be perfectly visible. During the day he does. As a motorist I am always thankful for oncoming cyclists to have bright lights. I see them so early that I can plan on it, move AFRAP with my car, giving oncoming cars lots of space and their drivers, in consequence, give the cyclist lots of space. The modern paranoia calling for super-bright lights is silly. It's spouted by people who haven't done simple tests. Nonsense. I did tests. If you want to be able to pull up to 15mph on singletrack or 25mph on a road with occasional debris on it those 1000 lumen lights are a safety feature. Because you see stuff. For slowpokes that is, of course, a different story. -- Regards, Joerg http://www.analogconsultants.com/ |
#76
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Is there an updated Dynotest somewhere?
On 2017-09-16 10:29, Radey Shouman wrote:
Frank Krygowski writes: On 9/14/2017 4:43 PM, Radey Shouman wrote: Frank Krygowski writes: On 9/14/2017 10:26 AM, Ralph Barone wrote: bob prohaska wrote: Sepp Ruf wrote: For Rob who might experience mental drag uphill from just having to see a big, heavy, non-laminated hub slowly revolving in the front wheel, the smallish Shimano DH-T780-1N, 1.5W 250mA class, might suffice[1] once he grows sick of the Soubitez. Best price I see is 96 euros a pair from CNC Hamburg on ebay, no overseas shipping available, though. http://www.ebay.com/itm/253093811841 [1] DRL does not require more than 100 lumens if you get the optics right. It's a bit puzzling how folks seem to excuse poor design in dynamo hubs when they're considerably more fanatic about optimizing every other part of a bicycle. In particular, the 3 watt standard is utterly archaic. Folks now are starting to use dynamos to power electronics, and I suspect most would opt for more than 3 watt lights if useful designs were available. I still don't understand why high-end builders like Schmidt don't use salient-pole armatures, which could be constructed from standard motor laminations (instead of the custom clawpole monolith used now). That would shorten the iron path dramatically, reducing reluctance, reduce the length of copper, reducing resistance. The performance gains can be traded for lighter weight, higher efficiency or higher power. Every motor builder in the world does it that way, why not dyamo hub builders? Maybe there _is_ a technical reason, but it certainly isn't apparent to me. The use of incandescent bulbs may have set the tradition, but it's certainly no reason to continue. At this rate I won't "get sick" of the Soubitez, I'll wear it out. bob prohaska Machine theory is a bit of a black art for me, but I suspect that the "less optimized" magnetics in hub dynamos provides the extra leakage inductance required to make it self regulate into a 12 ohm load. I fully agree that a less well regulated output plus a switching regulator could work very well with modern electronics. Is it feasible to use a switching regulator when you've got as much inductance as a typical hub dynamo? I'd have thought that causes problems. Happens all the time. Google "h-bridge", and notice all those diodes in parallel with the switching components, allowing current always to continue to circulate through some path. Typically the diodes are in the same package as the switching component, eg MOSFET. So spikes, etc. from switching inductors get to sort of bleed off through diodes? Is that the idea? Again, electronics isn't my thing. Roughly speaking, if you give a current across an inductor a reasonable path to follow, voltage will not spike until it finds an unreasonable path. I am familiar (OJT, not education) with the control of motors by switching amplifiers. During a large part of a typical cycle, when PWM is "off", currents actually circulate either through the high voltage or ground bus, slowly wasting power but doing no spectacular harm. The diodes are to provide a path, from ground to high voltage, during PWM dead time. I'm not personally familar with algorithms for controlling dynamos, but know that with motors in regeneration (braking), it is sometimes necessary to provide an alternate current path that dissipates power, in order to prevent unwanted voltage rise. It seems to me that controlling a permanent magnet dyanamo at part load is probably harder than some here think it is. Not really. If you have a battery in the system which any dectn vehicle should, even a tiny one, the controller can make sure that it never gets charge past an 80-90% mark. For Li-Ion this also greatly increases service life if the bike is parked for a long period while the battery is full. Now you always have a means to dumps so load without having to dissipate anything. ... Automotive and larger dynamos are normally controlled by varying the current through the field windings, an option that is not available for bicycles. But it could be. My guess is that claw pole armatures, with their self regulation by magnetic saturation, are actually a good practical solution. Bicycle lighting systems must operate usefully at low speed, and usually can't do anything useful with several times the power at high speed. Unless you have "real" lights like I do on both bicycles which consume about 3x what puny dynamo lights take in. Then there are smart phone, MP3 players and such. Sometimes I wish my bikes also had an A/C ... -- Regards, Joerg http://www.analogconsultants.com/ |
#77
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Is there an updated Dynotest somewhere?
On 9/16/2017 1:28 PM, Joerg wrote:
On 2017-09-16 09:16, Frank Krygowski wrote: On 9/16/2017 10:34 AM, Joerg wrote: No, cyclists get run over. Doesn't matter whether hill or not. A vehicle that travels at 1/4 the speed of motorized traffic or less is always at higher risk in the lane than traffic going at same speed. The risk goes up as the speed goes down. More bull****, Joerg, or at least, more ignorance of data. Motorcyclists have a fatality per hour rate roughly 30 times higher than bicyclists. You can't say that risk goes up as speed goes down. As an engineer you should at least try to find the real reasons. They can be summed up in videos like this: https://www.youtube.com/watch?v=cjtjexSg0SM meh. If that guy grows a pair he could working delivery on a fixie in NYC. Warning! Bicycle content: https://www.youtube.com/watch?v=_N-I8fpBx-4 -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
#78
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Is there an updated Dynotest somewhere?
On 9/16/2017 2:28 PM, Joerg wrote:
On 2017-09-16 09:16, Frank Krygowski wrote: On 9/16/2017 10:34 AM, Joerg wrote: No, cyclists get run over. Doesn't matter whether hill or not. A vehicle that travels at 1/4 the speed of motorized traffic or less is always at higher risk in the lane than traffic going at same speed. The risk goes up as the speed goes down. More bull****, Joerg, or at least, more ignorance of data. Motorcyclists have a fatality per hour rate roughly 30 times higher than bicyclists. You can't say that risk goes up as speed goes down. As an engineer you should at least try to find the real reasons. They can be summed up in videos like this: https://www.youtube.com/watch?v=cjtjexSg0SM But by your simplistic statement ("The risk goes up as the speed goes down") he would be in more danger if he slowed down! -- - Frank Krygowski |
#79
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Is there an updated Dynotest somewhere?
On 2017-09-16 11:54, Frank Krygowski wrote:
On 9/16/2017 2:28 PM, Joerg wrote: On 2017-09-16 09:16, Frank Krygowski wrote: On 9/16/2017 10:34 AM, Joerg wrote: No, cyclists get run over. Doesn't matter whether hill or not. A vehicle that travels at 1/4 the speed of motorized traffic or less is always at higher risk in the lane than traffic going at same speed. The risk goes up as the speed goes down. More bull****, Joerg, or at least, more ignorance of data. Motorcyclists have a fatality per hour rate roughly 30 times higher than bicyclists. You can't say that risk goes up as speed goes down. As an engineer you should at least try to find the real reasons. They can be summed up in videos like this: https://www.youtube.com/watch?v=cjtjexSg0SM But by your simplistic statement ("The risk goes up as the speed goes down") he would be in more danger if he slowed down! Put your thinking cap on for once. It is obviously the speed _differential_ that matters. Motorcyclist often go way faster than the rest of traffic or than is safe. Since they don't have a lot more protection that cyclists, other than better helmets and maybe leather suits, they are almost as vulnerable. Except they die more often because when they crash it's often at high speed. Without exception all the guys I know who had crashes on motorcycles didn't have those when flowing with traffic but when they were doing something stupid. Typically involving speed and acceleration. -- Regards, Joerg http://www.analogconsultants.com/ |
#80
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Is there an updated Dynotest somewhere?
On 2017-09-16 11:52, AMuzi wrote:
On 9/16/2017 1:28 PM, Joerg wrote: On 2017-09-16 09:16, Frank Krygowski wrote: On 9/16/2017 10:34 AM, Joerg wrote: No, cyclists get run over. Doesn't matter whether hill or not. A vehicle that travels at 1/4 the speed of motorized traffic or less is always at higher risk in the lane than traffic going at same speed. The risk goes up as the speed goes down. More bull****, Joerg, or at least, more ignorance of data. Motorcyclists have a fatality per hour rate roughly 30 times higher than bicyclists. You can't say that risk goes up as speed goes down. As an engineer you should at least try to find the real reasons. They can be summed up in videos like this: https://www.youtube.com/watch?v=cjtjexSg0SM meh. If that guy grows a pair he could working delivery on a fixie in NYC. Warning! Bicycle content: https://www.youtube.com/watch?v=_N-I8fpBx-4 Sure, I've seen those guy places like San Francisco. However, that is a very small minority of cyclists. With motorcyclists my impression is that the vast majority takes way too much risk and exceeds speed limits all the time. For example, on Salmon Falls Road where a few MTB trails start it is rare to encounter motorcyclists who are not riding like this: https://www.youtube.com/watch?v=ZkWWVryT1UE -- Regards, Joerg http://www.analogconsultants.com/ |
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