As for weather sealing, the Magnic is completely sealed as there are no external moving parts or switches. Whether it is entirely waterproofed down to 50 feet is something else.
I have Canti's on my bike and it worked using their simple bracket that attaches to the brake pad holder. I think the bigger problem is disk brakes as there is nothing at the rim.
I agree that the position of the iight is a bit awkward. I mounted my taillight on the right side as you ride on the left on NYC's one-way streets. It is the accepted practice here even if it isn't a universal one. Buses are on the right. If you were close enough behind me on my left you may not see it, but by then its already too late!
"When man first set woman on two wheels with a pair of pedals, did he know, I wonder, that he had rent the veil of the harem in twain? A woman on a bicycle has all the world before her where to choose; she can go where she will, no man hindering." The Typewriter Girl, 1899.
"Every so often a bird gets up and flies some place it's drawn to. I don't suppose it could tell you why, but it does it anyway." Ian Hibell, 1934-2008
I wish the full set on the new kickstarter was 1 front 2 rear, but I went in on it and added a 2nd rear -- I was tempted by the old version, but the lack of a standlight was a deal-killer. I'm tired of batteries running out on my beater bike, but am not ready to go dynamo on a very old bike with a wheel size that doesn't match any of my others -- this way, if I upgrade the bike I can just move the lights.
Blog says they sold the 1st batch, maybe the next one has been upgraded
Yea Calhoun bike in MN sent me a B&M Lyt it had no standlighjt either
sadly this will be the stock Brompton thing..
they burned me bad when I returned it , and stuff like gouging me $20 for a short piece of wire to hook up the taillight .. that they omitted even sending in the 1st place..
a place to avoid ..
This is the new one we've been talking about. Adds a standlight and is aiming to hit the German StVZO standard, which the first one didn't.
In any case, I wrote up a review of the Magnics that will hopefully answer provide some useful information as there seem to be plenty of questions and misinformation about them: http://www.bikeforums.net/showthread...-Magnic-Lights
Ultimately, you could compare watts to drag or lumens to drag -- take your pick, but you're going to have to get quantitative data on at least two variables here.
You've given some quantitative data for the two lights in your other thread (i.e. you can feel the drag from one but not the other), but you haven't actually measured it that I can tell. And while you've talked about how bright they are -- 30 lux vs 60 lux -- note that lux doesn't tell how much light the light emits, only how much light reaches one particular point (the brightest area) or the average over an area that they consider to be "the" important area -- "lux" is quite vague and not suited to comparisons regarding efficiency.
Comparing average lumens (average, because many dynamo lights have a visible flicker) would be ideal, and if you want to compare beam patterns you could count only the lumens that go where you want them, but then it becomes subjective.
As for typical values, I've heard that hub dynamos are around 50% efficient (so a hub generating 3 watts of power would generate about 6 watts of drag if it was 50% efficient), and modern LEDs tend to put out about 100 lumens/watt. I don't really have any idea how efficient the magnic light's electrical generation would be, but I wouldn't expect their LEDs to be particularly unusual.
Last edited by dougmc; 01-15-14 at 07:58 PM.
AFAIK Dirk has investigated the actual system efficiencies. IANA electrical engineer so I can't pretend to follow it in great detail. There is some info here: http://www.kickstarter.com/projects/...ess-bicycle-dy (under What's new in Magnic Light iC?) regarding the LED efficienty but I'd love to hear him explain it in greater detail. I can ping him and see if he can provide something more substantial if you're interested.
dhalbrook: Ok, I haven't yet taken a good look at Dirk's new Kickstarter page, but I am an EE and I'll try to assess what he says from that point of view. If you also gain some more insight from him, that would be great.
@dougmc: I applaud your rigor. I also support seeing some measurements. But on the optical side I think the ideal is to measure the ability to illuminate that which is useful to see, not to measure total light output, or electrical to optical energy conversion (lumens/watt). Depending on lumens to characterize optical output gives a product positive marks for spraying light where it isn't needed or might not be wanted.
A focus on lumens rather than illumination means that the best light is one with no light distribution control system - no light guides, lenses, reflectors, Fresnels, blackouts, et cetera. LEDs without lenses do not radiate full intensity into a 2pi space and the distribution is predictable, but it places a lot of its light where it might not be wanted or needed. Clearly one can use 10 degree (or narrower) factory-lensed LEDs to approximate spotlight functions. But that isn't what some of the better generator lights are doing (i.e. Lumos and Edelux 2), they are using sophisticated light distribution controls to approach the behavior of European automotive lights. For those of us who think that's the best model for bicycle light performance, illumination needs to be the target metric.
FWIW, I'm a huge supporter of dyno light systems in general so I'm not trying to denigrate them at all. Just trying to convey my observations about the Magnics to an obviously skeptical crowd. I'd love to see an independent reviewer (Peter White or Jan Heine perhaps) do more rigorous testing when the iC lights are ready so we can get some true apples to apples results.
I can easily agree with Zacster that the drag is imperceptible.
Last edited by Road Fan; 01-17-14 at 11:39 AM.
Last edited by njkayaker; 01-17-14 at 12:06 PM.
I suspect that the energy obtainable from the eddy currents is very limited (much lower than what is available from a generator hub). One issue is whether you can get enough light from the energy that can be produced.
We don't have any idea whether ratio of usable energy to drag is better than a hub generator. (Ideally, we'd want 100% usable energy to drag.)
Last edited by njkayaker; 01-17-14 at 12:17 PM.
Here is some detail on the magnets and LEDs he's using: http://www.magniclight.com/magniclig...rtseite/techno
Apparently something in the Cree Xb-D family.
Here is a chart about the LED efficiency, with accompanying text. Take from it what you will: https://s3.amazonaws.com/ksr/assets/...jpg?1387147866
2.Leds with 160 lumen per watt
The Magnic Light generator is tailored to the LEDs used, which reach almost 50% of the theoretically possible values- while good old standard systems barely attain 10-25 %:
Theoretically, the maximum white light you can obtain from 1 watt is appr. 350 lumen.However, good-quality LEDs only deliver about 40 lumen per watt (as used in many bicycle lights), which represents only 11% of the maximum. Light bulbs, on the other hand, only put out 10-15 lumen per watt, while theoretical maximum light possible is 685 lumen per watt (for green light). .
With high power LEDs one can reach appr. 80 lm/W, while the Cree LEDs used in Magnic Light deliver ~160 lumen per watt. This is possible because we feed each LED with less than 1 watt, which results in the ability to operate at temperatures below 35° C. This way, we harvest roughly 46% of the theoretical maximum white light, and hence 4 times more than standard LEDs.
Last edited by dhalbrook; 01-17-14 at 03:13 PM.
As for whether or not other people could feel the difference, you're right, it's hard to say. The difference is pretty clear to me, but maybe others wouldn't notice it as much. That's why it was only a guess.
Last edited by dhalbrook; 01-17-14 at 03:14 PM.