Just to be up-front, this instructable doesn't contain details on how to build induction coils or the lights themselves. I adapted commercially available magnetic induction lights to fit my bike perfectly, opening up the cases so that I could separate the lights from the coils.
A short video is below, showing the initial test of the separated coil, the finished setup, and how it looks at night:
Read on to see how it was done!
Step 1: "Reelight," Its Shortcomings, and Other Options
The problem with Reelights, though, is that they are mounted directly on the wheel axles. This makes the actual product small and compact (the coil and light are in one integrated unit) but has a number of shortcomings:
- The lights are very low to the ground, making them less apparent to drivers
- The arms can flex a bit as the magnets pass by them, so they have to be adjusted every so often
- The arms are kind of ugly
One last, big drawback of Reelights is their cost. They cost anywhere from $25 for a low-end one to $85 for a fully-featured pair, plus shipping. So I'm also including some links to help people get started with making their own induction coils, circuits, and lights.
- Here's a kit, called Freelights
- Here's a paper (PDF) that has basic DIY instructions. The real gold, here, is in the detailed calculations that will help you figure out how many turns you will need in your homemade induction coil.
- vbnicolau posted this awesome instructable on how to make your own circuit and lit using LEDs and a relay coil.
Step 2: Break Open the Reelight
This step has a number of close-ups of the internals of the Reelight, for others' reference. These pics are for the red rear light; the white front light was identical except for the color of the plastic cover.
Step 3: Re-Assemble LED Housing, Without Coil
I repeated these steps for both of my Reelights.
Step 4: Induction Coil Housing: Back Wheel
Now, to build the housings for the induction coils. For the rear housing, I wanted an aerodynamic housing that would nestle into the rear triangle of my bike frame, right next to the axle. I cut this from a satellite dish (same one that provided me with the audio cables and jacks. Everything was carefully measured out and sketched onto the satellite dish, and then I cut out the housing and shaped it using a dremel.
The induction coil was then sealed with large amounts of hot glue and mounted into the housing. Hot glue was also used to mount the housing to the frame. Afterwards, I did a quick test to make sure that the wheel was inducting a current in the circuit, and that it indeed lit up the LEDs.
Step 5: Induction Coil Housing: Front Wheel
Step 6: Finishing Touches
There's no noticeable drag while riding, and the lights have been working quietly and reliably for many months, now.