By December 20, 2007

Rare earth magnet as red light triggering device review

One of the day-to-day annoyances of riding a motorcycle is traffic lights. Some lights are on timers, but most of them use an electrical loop buried beneath the asphalt. The loop detects when a metallic object is overhead, and starts the light change routine.

Unfortunately motorcycles have a hard time triggering such devices, especially when the bike is mostly aluminum and plastic like Cylon. A clever member of the FZ6 forum I belong to mentioned that he used rare earth magnets to cycle the light. I was skeptical, but after sitting at a left-turn signal for five minutes on evening I decided to try it.

Like most off-the-wall Gibberish purchases, at least it would make for an interesting post.

I bought two black rubberized BX084PC-BLK magnets from K&J Magnetics. Each magnet had a pull strength of sixteen pounds. They arrived promptly, along with instructions not to put your fingers in between two magnets that may be attracted to each other. Something for my motorcycle and something dangerous? This is my kind of item.

Having a mostly-aluminum bike presented certain unforeseen challenges when I tried to attach the magnets. I wound up attaching the small black rectangles near the kickstand. The mounting plate is apparently steel, and the magnets stuck like glue. They mounted a little crookedly, but the pull was so strong I shrugged and muttered, “fuck it.”

I foolishly rode my rear tire bald, so it took me awhile to actually test the magnets out at a stop light. I was delayed further because I had “company” at my one test light for a few days in a row. There’s a double-left turn coming out of my local Starbucks, and with all sorts of consumertacular stores around I didn’t know if the magnet was doing the work, or if the car nearby was triggering the light. I bought the magnets at the end of September, to give you an idea of how long I’ve been waiting to write this article.

I finally had three back-to-back tests in isolation this week. Sure enough, the magnets provided enough of a disruption to initiate the light change sequence. I waited no longer than I would while driving my car, and was never skipped over.

I purchased my two magnets for less than $9 shipped. It was well worth the money, and sure beats the typical alternatives for solving this problem: tilting the bike over, or extending the kickstand, or running the light.

Posted in: motorcycling, review

9 Comments on "Rare earth magnet as red light triggering device review"

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  1. Ed says:

    You didn’t give it rankings? 5 STFU?

  2. Ninja Mary says:

    Teach would like to know if you could get an electromagnet and use it to trigger the light multiple times so it thinks that there are multiple cars at the light.

    It’s 5:30 am…so if it’s silly cut him some slack ;oP

  3. When they said you shouldn’t stick your fingers between two magnets, they sure weren’t lying! That stuff can really smush your fingers, but good! Don’t get hurt playing with magnets kids! 🙂

  4. Huh, I thought lights were weight-triggerd. Didn’t know magnets were involved.

  5. Justin says:

    Yeah we have some rare earth magnets at work. One day (I had apparently forgotten to turn my brain on)I was walking with one in each pocket and I walked between two rows of cabinets. I came to an abrupt stop.

    Then I began cogitating on what would have happened if the magnets slammed together… while they were still in my pockets….

    I think that’s the closest I’ve came to self castration.

    Anyway, I need to try them on my KLR because I have a light by my house that refuses to turn for me….

  6. American Magnet says:

    do you know if your allowed to do this or do they not care about motorcycles?

  7. drfaulken says:

    Hi AM, I am not certain if it is legal or not. I know that tampering with a stoplight is illegal; however this isn’t making the light act any differently than it would if a car were present instead of a motorcycle.

    All of that being said, I may need to buy another magnet. There are still a few lights that don’t trigger along my semi-usual routes.

  8. magnetic stimulation says:

    Wow, I had no idea that they put an electric beneath the asphalt to change the lights. Thanks for that interesting tidbit. I always thought all lights were on timers. I guess that makes sense, especially considering that some lights really don’t get much traffic a certain way. Using that device might not be a legal thing to do, though. Maybe it is, I’m not sure. I guess if its doing the same thing as a car does. But couldn’t it be messing up the sensor if you use it? I don’t really know myself.

  9. Bob Ruby II says:

    To exchange the $9 cost for some labor you can tear apart an old Hard Disk Drive from your least favorite PC. Inside is a nice Neodymium (rare earth) magnet with more than enough pull to trigger a light.

    Older is better, the magnets are larger and they have little screw holes in just the right place to put a cable-tie or twist tie (if you are really desparate).

    The older drives also only needed a phillips head to open them up.

    – Uncle Bobsquatch