EEVblog Electronics Community Forum
Products => Crowd Funded Projects => Topic started by: thm_w on January 09, 2018, 10:36:47 pm
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https://www.kickstarter.com/projects/dynamodirk/magnic-microlights-non-contact-driven-brake-shoe-b/description (https://www.kickstarter.com/projects/dynamodirk/magnic-microlights-non-contact-driven-brake-shoe-b/description)
The guy has done two kickstarters in the past, and the previous lights worked but contained a fairly large neodymium magnet assembly (https://www.magniclight.com/en/technology/magnets/45-magnetrings (https://www.magniclight.com/en/technology/magnets/45-magnetrings)).
Essentially how it works is you have a spinning aluminum (rim) or steel plate, and the strong magnetic field creates eddy currents. If you have every dropped a magnet inside a copper tube, you will understand. The magnets will spin, creating a strong moving field, which can be captured in a coil or multiple coils of wire (I assume this is how he's doing it).
The pictures are a working 3D printed prototype. How he's managed to miniaturize the technology is impressive. I suppose its just a much smaller generator sitting inside there, current doesn't have to be too high for a small red LED. I have not seen any internal photos though, other than of the LED driver board (contains active rectifier).
I haven't personally used his product, but have used another style: https://www.bikelight.ca/collections/city-bikes/products/city-supreme-light-set (https://www.bikelight.ca/collections/city-bikes/products/city-supreme-light-set)
Its not really usable IMO, two small LEDs don't provide enough brightness.
There are also some versions which require sticking a magnet onto the spokes, which I don't care for.
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It's an interesting device, though with some fairly useless "add on" features such as turn signals.
However it looks like you can only wear away a tiny fraction of the brake shoe before the body of the light would be pushed against the rim? I must have missed something obvious, as that would seem to be a major flaw.
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It's an interesting device, though with some fairly useless "add on" features such as turn signals.
However it looks like you can only wear away a tiny fraction of the brake shoe before the body of the light would be pushed against the rim? I must have missed something obvious, as that would seem to be a major flaw.
Yes I agree the turn signal feature is useless and is probably just a distraction (how often will you accidentally trigger it). Its only on the higher priced "smart" model.
Good eye on the body of the light rubbing. I see a small rail that it looks like would be used to adjust the distance of the module. So presumably as the shoe wears, you would need to slide the light module further out. Which is annoying, but OK compromise to keep peak efficiency/coupling.
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Why would I want to mount the lights on the brake shoes anyway? They get wet and dirty down there. Strange idea...
Also, it seems that these are not certified for use on public roads -- you can only install (and use) them as secondary lights, at least in Germany, probably most of Europe. That totally defeats the purpose in my view, which would be to keep a minimalist look of the bike.
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Why would I want to mount the lights on the brake shoes anyway? They get wet and dirty down there. Strange idea...
I can see the logic; the method of power generation means it needs to be close to the wheel rim and building it into the brake shoes means it's a quick and simple add-on for any bike using caliper/vee/centre pull brakes with no special brackets needed.
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Why would I want to mount the lights on the brake shoes anyway? They get wet and dirty down there. Strange idea...
I can see the logic; the method of power generation means it needs to be close to the wheel rim and building it into the brake shoes means it's a quick and simple add-on for any bike using caliper/vee/centre pull brakes with no special brackets needed.
Well, alternatively there would be the revolutionary concept of attaching the power generator close to the rim -- at the brake shoes, if one desires -- and mounting the actual lights elsewhere. I heard that so-called "wires" have been used successfully to transport electrical power. ;)
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Why would I want to mount the lights on the brake shoes anyway? They get wet and dirty down there. Strange idea...
I can see the logic; the method of power generation means it needs to be close to the wheel rim and building it into the brake shoes means it's a quick and simple add-on for any bike using caliper/vee/centre pull brakes with no special brackets needed.
Well, alternatively there would be the revolutionary concept of attaching the power generator close to the rim -- at the brake shoes, if one desires -- and mounting the actual lights elsewhere. I heard that so-called "wires" have been used successfully to transport electrical power. ;)
I agree, that's an obvious and easy fix for the problem of the light positioning, but doesn't fix the problem of the surface of the generator and the surface of the brake shoe being almost level.
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In the US as I understand it we just have to have lights, we don't have to have any approval for the lights. As long as it is a bicycle, even an electric one in order to ride at night you just have to have a front and rear light and reflectors. So its sufficient enough for one to strap two flashlights on your bike one with a red cello tape on it for the rear and your golden. Truth be told not many people in the US ride bikes though, just look at our collective waist lines.... |O
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It's an interesting device, though with some fairly useless "add on" features such as turn signals.
However it looks like you can only wear away a tiny fraction of the brake shoe before the body of the light would be pushed against the rim? I must have missed something obvious, as that would seem to be a major flaw.
In my experience bicycle brake shoes last a very long time, in fact I don't think I have ever had to replace one. I'd imagine a minor adjustment whenever the bike is being serviced for other things would be sufficient to solve that particular problem.
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In my experience bicycle brake shoes last a very long time, in fact I don't think I have ever had to replace one. I'd imagine a minor adjustment whenever the bike is being serviced for other things would be sufficient to solve that particular problem.
Depends heavily on the weather, how hilly your ride is, pad material, etc.
In the best case dry weather they can last up to 5,000 or 10,000km. Worst case in the winter with dirt and grit, could be <1,000km. My winter bike was somewhere under a year of use.
But yeah, relatively easy to adjust something like that if you do any maintenance.
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Its a nice idea, would fit my riding pattern of mostly long road rides *aiming* to be home before dark, but very rarely get caught out needing lights, but use them so rarely I never know how much battery is left.
I assume it doesn't work for carbon rims?
They'd have probably been better turning it into a charging system to top up a battery pack for phone or gps-cycle-gadget though
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Depends heavily on the weather, how hilly your ride is, pad material, etc.
In the best case dry weather they can last up to 5,000 or 10,000km. Worst case in the winter with dirt and grit, could be <1,000km. My winter bike was somewhere under a year of use.
But yeah, relatively easy to adjust something like that if you do any maintenance.
Wow I don't think I've ridden 1,000km in 20 years. I'm not a serious cyclist though.
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Its a nice idea, would fit my riding pattern of mostly long road rides *aiming* to be home before dark, but very rarely get caught out needing lights, but use them so rarely I never know how much battery is left.
I assume it doesn't work for carbon rims?
They'd have probably been better turning it into a charging system to top up a battery pack for phone or gps-cycle-gadget though
Correct wouldn't work for carbon, though some really old carbon rims still had a strip of aluminum for the braking surfaces.
If you want enough to charge a phone you could get a dynamo wheel, but even then its just 3 watts (1 (https://www.huntbikewheels.cc/products/hunt-superdura-dynamo-disc-road-bike-pack-cx-wheelset-120kg-rider-weight-1939g-24deep-25wide) or 2 (https://www.chainreactioncycles.com/fi/en/prime-audax-650b-alloy-dynamo-wheelset/rp-prod187137), and price is high.
I ended up using 3x 18650 cells in my seatpost, then charge them every few weeks. Weight: ~150g, ~35Whr (3W of lights would last 11hrs).
Wow I don't think I've ridden 1,000km in 20 years. I'm not a serious cyclist though.
Yeah you need to consistently ride to build up km's to the point you actually wear through pads/bearings :)
But its not impossible if commuting a short distance regularly: 20km * 250 work days = 5,000km per year.
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I ended up using 3x 18650 cells in my seatpost, then charge them every few weeks. Weight: ~150g, ~35Whr (3W of lights would last 11hrs).
Thats a neat idea, Di2 style. Perhaps I was doing a lot of night riding or commuting, then a dyno-hub might make sense, I should just learn to be less forgetful with batteries!