Cable geniuses at my school
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The logic of this escapes me entirely, except that maybe the manufacturer wanted to save on a few metres of wiring.
Considering relative prices of copper and plastic, it might be justified.
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Just because it's something "people used to do" doesn't mean that it is or ever was a good idea.
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Reply to specific parts of posts in order the way people used to before Microsoft got everyone to use its bastard Outlook-taught method of quoting messages, you mean?
It's usually better to reply to a whole thought, which typically means only by paragraph (unless you're picking up on a side-clause or other aside without engaging in the overall paragraph). Without that, you easily get down to considering the feng shui alignment of the letters and rot like that: pendantic dickweedery, except without being properly pendantic.
Proper debate ought to not seek to misrepresent what the other side says.
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Proper debate ought to not seek to misrepresent what the other side says. Also your mother likes HD-DVDs!
What did you say about my half-assed joke wherein I pretend to misrepresent what you said?
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Just because it's something "people used to do" doesn't mean that it is or ever was a good idea.
No, because it’s infinitely better to quote a whole message and then in front of it, put either a single-line reply, or have to rehash a lot of points the other person made just so it’s clear what you’re replying to — when you could insert your replies after the relevant parts of the original message, so it’s obvious what you’re talking about. (Note that I’m talking about email here, not forums where at least top-replying is luckily uncommon.)In other words: Just because it's newer doesn't mean that it is or ever will be a good idea.
Proper debate ought to not seek to misrepresent what the other side says.
That’s not the same as only quoting what you see as the relevant parts of the other person’s message.
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Well, if you need this crutch in order to be able to actually make some kind of coherent argument...
... and please, be a bit more original. Not to mention that I somewhat doubt that your method is "older".
You still come across as a old geezer with "git of mah lawn!" outlook on what present day looks like compared to the past. You paint people with a broad brush, are unable to actually present any evidence (oh, great, it's your opinion! Yeah, well, an opinion is not really worth much) and generally dismiss problems because, oh yeah, you learned to cope with your problems!
Great! What a fine boy you are! Do you want a pat on the back for that, or what? THIS is what I'm talking about here: This snide attitude of yours which sneers on other people's supposed lack of intestinal fortitude, this moronic: "Oh, but you could if you only wanted to!" which yields someone preaching from the lofty heights of his superiority complex because he can't really comprehend that not everyone thinks the way he does.
Plus, I'm also not quite sure if you expect the teachers to carry people in wheelchairs up the stairs until an elevator has been built. Or do you think they conjure them up out of thin air, instantly? Or do you expect a disabled person to decide one year or more in advance to which school he or she wants to go to?
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Paging @boomzilla.
Eh...what? Why am I here? Oh...
And, yeah, we get it: You're a tough guy. Not everyone is, though.
I tell my kids to shut up and rub some dirt on whatever is hurting. They look at me like I'm crazy, but I'll tell you, we considered ourselves lucky to have that pinch of dirt.
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I bought a new bicycle a few years ago, and to my mild surprise it came with a battery-powered taillight despite having a dynamo in the front wheel hub to power the headlight. The logic of this escapes me entirely, except that maybe the manufacturer wanted to save on a few metres of wiring.
Considering relative prices of copper and plastic, it might be justified.
Actually, I suspect they are thinking of safety. It's good if the tail light stays on, even if the dynamo is stopped, such as if you're parked on the edge of the road.
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... and please, be a bit more original. Not to mention that I somewhat doubt that your method is "older”.
I didn’t say that. I was just replying to your saying that something which is older isn’t automatically better — that’s true, but it also doesn’t automatically follow that something newer, is.You paint people with a broad brush
No, I treat people the way they they appear to me. Which is to say, I try to not hold any particular opinion about anyone I meet except based on what they do and say. I’ll be the first to admit this doesn’t always work, but you’re not going to accuse me of being biased against groups of people. “Oh, but earlier you called people hypochondriacs when they have legitimate medical conditions!” No, I call people hypochondriacs when they could cope but choose not to because we live in an extrovert society where you have to complain about things and so get sympathy for yourself. If that equals having an old-fashioned attitude, well I suppose then I do. I still don’t see why this is so utterly wrong.Oh wait, maybe what’s happening is that you began taking this discussion personally the moment I said I think there are people who act that way, as if I said you had problems that you might not have if only you had more moral fibre. Did I say anything of the sort? No, I don’t think I did.
someone preaching from the lofty heights of his superiority complex because he can't really comprehend that not everyone thinks the way he does.
No, I know not everyone thinks the way I do. That doesn’t mean I can always understand their points of view, or their reasons for having them, but you’re not telling me that I think everyone should think the way I do.
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It's good if the tail light stays on, even if the dynamo is stopped, such as if you're parked on the edge of the road.
True, though that could also be solved with a capacitor in the taillight, saving the need for a change of batteries and for the cyclist having to remember to turn on both lights.
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My front light works with a dynamo (always on), light sensor, and capacitor. It automatically turns on, and stays on for at least a minute or so after I stop moving.
The rear light has a battery and a button
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True, though that could also be solved with a capacitor in the taillight, saving the need for a change of batteries and for the cyclist having to remember to turn on both lights.
What are you, one of those people who insist on perfection?
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The rear light has a battery and a button
You could probably fix that with a few feet of wire and a soldering iron, you know.
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My front light works with a dynamo (always on), light sensor, and capacitor. It automatically turns on, and stays on for at least a minute or so after I stop moving.
Mine’s got a button to turn it on and off (no sensor, that was only on a more expensive model of the same bike) but since the button got wonky after only a few months I decided to just leave the light on at all times, day or night. Since the dynamo’s in the hub I have to pedal against its resistance anyway, so I figured I might as well get some light out of it.What are you, one of those people who insist on perfection?
I’ll settle for convenience :)
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Since the dynamo’s in the hub I have to pedal against its resistance anyway, so I figured I might as well get some light out of it.
Actually, that's not the way a dynamo works. You'll only experience a counterforce if the circuit is closed so that a current can flow - because it's the induced current which creates a magnetic field which in turn works against the external magnetic field.
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because it's the induced current which creates a magnetic field which in turn works against the external magnetic field
Lenz's Law, isn't it?
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You could probably fix that with a few feet of wire and a soldering iron, you know.
Depends on if dynamo can provide the same current as the battery.
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Lenz's Law, isn't it?
Indeed. Or like my own Physics teacher told us:
"Think of the cable as a particularly lazy pupil. He hasn't had a magnetic field the whole time and now he still doesn't want a magnetic field. That is inertia!"
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Depends on if dynamo can provide the same current as the battery.
The better question would be: Can you provide the same voltage as the battery. Basically, the dynamo has two variables:
The speed with which it rotates and the counter force you encounter while rotating it.The rotation speed determines the voltage (it's also dependant on the number of turns in the coils and the strength of the (permanent) magnets, but those are usually fixed values for bicycle dynamos), the counter force is dependant on the resulting current.
Essentially, it's only dependant on your muscles (and whether the dynamo is provided enough torque and doesn't slip) whether you manage to provide the lights with enough energy.
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I was thinking of possible extra mechanical resistance compared to a hub without one, but I didn’t know it produces more resistance when providing electricity — though that’s pretty obvious when I think about. Still, since I don’t feel the bike pedal any lighter with the headlight turned off, I doubt it’ll make much of a difference in the end.
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Where did you think the energy for the lights came from? ;)
The whole concept becomes very noticable if you simply short-circuit a dynamo - that will be an absolute bitch to turn, plus you'll most likely fry the dynamo due to overcurrent.
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I know that — it’s just that the times I’ve turned a bicycle dynamo by hand¹ when it wasn’t connected to anything, it still had noticeable resistance so I figured this was regardless of whether or not it’s producing any electrical current.
¹ Though this was with old-fashioned ones that you manually have to put onto the wheel, not hub-mounted ones that I suspect are designed to have relatively little resistance because they can’t be disengaged from the wheel.
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it’s just that the times I’ve turned a bicycle dynamo by hand¹ when it wasn’t connected to anything, it still had noticeable resistance
Which sounds to me like it needed lubrication. Or a damn good servicing.…and the Chrome speelchucker vomits over smart quotes…
INB4
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Depends on if dynamo can provide the same current as the battery.
It powers the front bulb, so unless the two bulbs are wildly differently specced, it should.
Oh, it might mean the two bulbs together are somewhat dimmer. If you're dealing with LEDs, maybe they won't work at all. But it might work.
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Oh, it might mean the two bulbs together are somewhat dimmer. If you're dealing with LEDs, maybe they won't work at all. But it might work.
Since bicycle bulbs are usually wired in parallel, as long as you can maintain the same speed as with just one bulb, they will be of the same brightness. It's just more exhausting because the counterforce is higher due to a higher current.
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It's just more exhausting because the counterforce is higher due to a higher current.
That sounds annoying. How much harder is it to pedal with one of these attached, and how long does a battery last?
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That sounds annoying. How much harder is it to pedal with one of these attached, and how long does a battery last?
Well, our dynamos in Germany are supposed to provide 6 or 12 Volts for a maximum of 500 mA current, so you need to provide at least 3 to 6 Watt. Considering power loss due to friction, resistance and other factors, that might go up to 4-5 W respectively 7 to 8 W (though I'm just guessing here, truth to be told, wasn't able to find hard numbers for the level of efficiency of bicylce dynamos).
Now, if you're using a "normal" bicycle (what we call a "Hollandrad"), you'll need about 160 Watt to achieve a speed of 23 km/h to put that into perspective (determined by using this form here: http://www.kreuzotter.de/english/espeed.htm)
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Which sounds to me like it needed lubrication. Or a damn good servicing.
Dynamos of the old-fashioned kind like this:
… if you ask me hardly ever get serviced, almost certainly not in this country anyway. After a few years, the only cleaning my old bike got was when I had to ride it through the rain — and I owned it for 24 years before part of the gearing in the back hub broke, and I finally figured it might be better to just buy a whole new bike :)
That sounds annoying. How much harder is it to pedal with one of these attached, and how long does a battery last?
With a dynamo like that pictured above, most people seem to hardly ever use them even when it’s dark because “they make it heavier to pedal.” Which they do, but after maybe a minute or so you don’t feel that anymore. Truth be told, batteries last ages with a modern LED taillight — my chief complaint with them is having to turn them on separately from the headlight.
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With a dynamo like that pictured above, most people seem to hardly ever use them even when it’s dark because “they make it heavier to pedal.”
I don't use them mostly because they don't work anymore - either because it's wholly broken, or because it doesn't stick to the tire after all those decades.
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batteries last ages with a modern LED taillight — my chief complaint with them is having to turn them on separately from the headlight.
That, also, seems like a thing you could fix with a soldering iron and some wire.
Probably moreso than the other thing I said--just slave the back light to the front button.I'm a bit surprised nobody's actually come up with a system that works out of the box that way, unless it has and I just don't know about it.
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The point of independent rear lights is not having the wire. Because cheap materials and broken wires means no lights ever.
I've seen systems where the rear light has a light sensor and a motion sensor, so it goes off automatically when the bike is stored. LEDs last for ages on a AA or AAA battery, but not when on 24/7.
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The whole concept becomes very noticable if you simply short-circuit a dynamo - that will be an absolute bitch to turn
That's how the blade-brake in a circular saw works. It's fun to take a decent electric motor (like one out of a remote controlled car), short the terminals together, and try to turn the shaft. If the motor is good, it will be nearly impossible to turn.
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That's how the blade-brake in a circular saw works. It's fun to take a decent electric motor (like one out of a remote controlled car), short the terminals together, and try to turn the shaft. If the motor is good, it will be nearly impossible to turn.
Yep -- with today's high-power motors, you could probably generate enough brake force to stop a hypothetical electric 18-wheeler that way, or keep it on speed on a several % downgrade. (You'd probably have a set of resistors hanging out somewhere instead of just shorting it, but yes -- traction motors are quite good these days...)
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The concept scales up nicely.
These things absorb hundreds of horsepower.
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I wonder what the maximum dynamic brake absorption of a modern road locomotive is...
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I wonder what the maximum dynamic brake absorption of a modern road locomotive is...
Eddy current brakes differ a bit from simply short-circuiting an electric motor, though. An Eddy current brake is usually created by moving a metal disc through an inhomogenuous magnetic field.
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Eddy current brakes differ a bit from simply short-circuiting an electric motor, though. An Eddy current brake is usually created by moving a metal disc through an inhomogenuous magnetic field.
Verily true -- the technologies differ in subtle ways.
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With a dynamo like that pictured above
They don't work very well in winter when things ice up.
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Or when it’s raining heavily. Or when the spinning bit at the top is worn. Or when the side of the tire is worn. Or when it’s not been adjusted to sit against the wheel correctly. Or when you put it against the wheel.
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You'd probably have a set of resistors
Or, if you're clever, you'd charge a capacitor (well, or something similar) while breaking and re-use the energy when you want to go forward again:
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Have you seen this type?
These work by induction
All products
Award winning battery free bike lights and rechargeable battery bike lights. Buy clever daytime running lights from Reelight for your bicycle. Designed and developed in Denmark. Free shipping in EU over €80.
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Have you seen this type?
These work by induction
All products
Award winning battery free bike lights and rechargeable battery bike lights. Buy clever daytime running lights from Reelight for your bicycle. Designed and developed in Denmark. Free shipping in EU over €80.
Pretty much everything using magnets uses induction :p
(There may be exceptions but I'm not coming up with any at the moment)
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everything using magnets uses inductio
I'm well aware. The point was there is no mechanical connection to the wheel, as with a conventional dynamo.
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- You linked to the "All products" page. Which one are you talking about?
- Do they have an English page (granted, I'm on mobile here so I might have missed some small button).
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I meant to link this product.
https://www.reelight.com/dk/produkter/sl200/sl200/sl200-magnet-cykellygte-set-4-magneter/
I'm on mobile too, Upper right corner the button that says "sprog".
Direct link to English version:
https://www.reelight.com/en/products/sl100/
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Disco fucks that up for some reason... 😢
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That's sort of like a linear Eddy current generator.
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Regenerative braking - Wikipedia
