When it comes to power for bike lights, there are two main options: batteries that have to be charged/replaced, and dynamos. The latter either push against the side of the tire, have to be pre-built into one of the hubs, or require magnets to be mounted on the wheel – in all cases, dynamos also create a slight braking effect when in use. German inventor Dirk Strothmann's Magnic Light iC, however, lets the wheel spin freely and doesn't require the installation of anything other than the compact light itself. Is it too good to be true? We tried out the latest version, in order to find out.

First introduced as a Kickstarter project in 2012, the Magnic Light is mounted a few millimeters from the bike's wheel rim, and utilizes what are known as eddy currents. Putting it simply, these are electrical currents that are induced in a conductor, when that conductor is exposed to a changing magnetic field.


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"Relative movements of magnets and neighbored conductive material induce eddy currents in the conductive material – in our case the metallic rim," Strothmann explained at the time. "These eddy currents have their own magnetic fields which are absorbed by the Magnic Light generator kernel and by this way produce electric energy."

Although it is possible to buy individual Magic Lights, we received a complete package that included two headlights and one tail light. That kit contains all the hardware necessary for a variety of mounting options, which was actually a little intimidating at first. None of the various bags of brackets, nuts and bolts are labelled, leaving the buyer to figure out which ones they should be using.

On our setup, the lights got attached to the front and rear brake arms, which proved to be fairly easy once we determined what bits we needed. Some fussing was necessary, however, in order to get the spacing between the lights and the rims just right – too wide of a gap and the eddy current effect won't work, but too narrow and the lights will rub against the rims. Fortunately, once that spacing is set it can be locked down and left, with the lights themselves temporarily detaching from the mounting brackets as needed via a quick-release mechanism.

And yes, they definitely do work.

All three lights illuminated us nicely on our night rides, with no batteries or wheel-rubbing involved. Supposedly they do still create a very small amount of wheel resistance, but we certainly couldn't detect it.

Each one puts out about 40 lumens at a cycling speed of 20 km/h (12 mph), so they're definitely more "be-seen" than "light up the road" lights, but that's fine for commuting on already-lit streets. The light output is also quite smooth and consistent, thanks to the inclusion of a capacitor that also allows the lights to remain lit when the user stops at intersections.

One feature that's new to this incarnation of the product is the ability to choose between four different flashing modes, and it's actually one that we could have done without.

Because there are no physical switches on the lights, users have to change modes by first spinning up the wheel for a minute in order to charge the capacitor, then suddenly stopping the wheel and waiting for the light to start flashing, then spinning the wheel once again until the light resumes flashing, and then stopping the wheel and waiting for the light to flash yet again, indicating that it's entered the next mode.

It's a pretty confusing process, and to be honest we never were sure that we entirely got the hang of it. Fortunately, as with the mounting process, it's something that you'll presumably just do once and then forget about. You could not even bother doing it at all, just sticking with the factory default mode.

All in all, though, if you don't want to bother with batteries but also don't want the friction of a dynamo slowing you down, the Magic Light iC is certainly the way to go. The three-light set sells for €158.82 (about US$182).

Product page: Magnic Light iC

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