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MAKE subscriber Justin Shaw has posted a project on Instructables for a bike brake lighting system that features lights on the ends of a bicycle’s handlebars, controlled by an Arduino and a Pololu 3-axis accelerometer. He’s even offering a $35 prize to the first person who follows his plans and posts proof of a successful build.

Bar End Brake Light: BEBL

Gareth Branwyn

Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of a dozen books on technology, DIY, and geek culture, including the first book about the web (Mosaic Quick Tour) and the Absolute Beginner’s Guide to Building Robots. He is currently working on a best-of collection of his writing, called Borg Like Me.



  1. Shadyman says:

    Bonus points if you add a yellow LED for nighttime travel.. even more if you add turn signals based on accelerometer input.

  2. japroach says:


    shady: sadly a turn signal is useless unless its manually controlled.

  3. Angus Og says:

    Well it’s a neat idea but in reality, what use is brake light on a bike? How is it any more useful than a flashing or steady red light? At bicycle speeds an indication of braking is not really of any use to other road users.

    Also, a cheaper and more robust implementation would be a simple switching mechanism at the brake levers.

  4. BusterB says:

    In addition to the ‘robust’ comment – exactly how is someone, presumably a driver in a vehicle, supposed to see these lights? It is fine if one is at an oblique angle, but even directly behind a near-anorexic woman the lights are obstructed. So of what use are the lights?

    And of what use are the lights in bright daylight? Useful, or useless?

    1. Marc says:

      @BusterB: I think that is his young daughter, not an near anorexic woman.

      I don’t think this supposed to be a perfect and final solution. Looking at his blog, it is one in a line of iterations over bike light & brake light designs as well as general arduino tinkering. For instance, check out his uber light:

      This form factor does have one bonus, you can plug those into the handlebars without any addition to the bike or modification to the braking mechanism.

  5. Anonymous says:

    That music R to L fade was annoying!

  6. doroti says:

    “At bicycle speeds an indication of braking is not really of any use to other road users.”

    … so cars going 30mph don’t need to signal stopping either then? Sorry that’s just wrong. I can go 45 mph on big downhills and I’m just a commuter, not a racer. Realistically I often do 30 on mild slopes and this is occasionally necessary to beat traffic for a short stretch. On flats I typically cruise at 18mph. Amazingly drivers often have no regard for life and will actually tail gate a cyclist at such speed. I can stop very fast. I really like this idea. Some kind of water spray out the back would be nice too.. may. Drivers wrong preconception that bikes move at a crawl is a huge cause of dangerous situations usually involving being cutoff.