“A popular myth is that a strong permanent magnet will do the trick. This is complete nonsense, since a magnet produces a constant (D.C.) field and can not change the inductance of the sensor loop, nor can it in any way pull the frequency of the sensor’s oscillator. One must inject a signal at or near the operating frequency of the loop in order to cause the sensor to notice a change. Although some will swear that their magnet is effective, it is possible that they have found a sensitive sensor, or that (more likely) another vehicle is present on an adjacent or opposite sensor and is activating the light sequence. “

Having tried both methods, I prefer the shoe-mounted one — I carved some lugs out from the center of the sole (with a Dremel-type tool) so the magnet sits flush and doesn’t interfere with pedaling. The advantage to this method is that you can put the magnet directly on the buried loop strip, triggering the stoplight cycle.