My mate in Sweden sent me this about bike lights that seem to work a bit like a dynamo but there appears to be no contact between the unit and the wheel
. I can't see how you are generating power without contact or without drag, but that seems to be what is claimed
http://www.magniclight.com/index.php/en/
Wasn't there a turbo trainer that worked with the same principal but in reverse, using a magnetic field to resist the motion of the back wheel.Â
Anyway Mr Joule would like a word about his little law as there will be drag if it works. Having said that they look like the doomed dregs left in Aldi's central aisle of randomnessÂ
I said the same, like otherwise there must be a law of physics being dodged or something (as sir Isaac Newton said)
Apparently strong magnets can exert a force on aluminium  - magnets don't attract alu like they do steel but they can sort of swirl the electons around inside alu when magnets and alu are moving close to each other. More typically you'd use this effect for a sort of contactless braking - if the magnet is fixed, but I'd imagine in this case the magnets are able to spin and generate power.
Theres some interesting images here of how aluminium can behave around magnets
Anyway Mr Joule would like a word about his little law as there will be drag if it works.
you'll see the claim on the site is actually  'no noticeable drag'Â
SJS cycles sell something similar but with  the lamp separate from the little generatorÂ
Ah, now I am down an eddy current wormhole. Interesting 🤔Â
Chapeau sir
I have those, got them from family in Denmark, NOT part of the brake pads, but same (contactless) principle. Of course, there is drag, but very little as contactless, just the magnetic fields.
How bright are the lamps? Are they genuinely good lights?
We used to sell a similar light in the shop (in Edinburgh) about 16-17 years ago. I can't recall the make. They were OK for a bit of commuting but paled (see what I did there) compared to the better battery lights available even then. Useful in that they were permanently attached, no battery to charge and weren't likely to be pinched off the bike. I think we eventually gave away the last few sets.Â
There was something similar a few years ago. Magnet fixed to the fork and stays and then the lights on the spokes would illuminate on the spinning wheels. Small capacitor allowed illumination while stationary for short periods.
How do you attach them to the bike?
Surprised no one's mounted a motorcycle style rotor/stator arrangement from a disk brake rotor?Â
It'd be quite nice to have a dynamo setup for winter and take it off for big summer rides without needing two sets of expensive wheels.