A Longboard Speed And Distance Computer


Why should cyclists have all of the fancy toys? Bicycle computers are very common these days but you won’t find similar hardware for skateboards and longboards. [KobraX22] isn’t taking it lying down. He built this speed and distance computer for his longboard. It doesn’t use very many components and should be easy to install.

The device monitors the rotation of one of the wheels by mounting a reflectance sensor on one of the trucks. It points toward the inside of a wheel which has a piece of black tape on it. Every time the tape passes it prevents the IR led from reflecting back at its paired receiver. This lets the Arduino count the revolutions, which are then paired with the wheel diameter to calculate speed as well as distance traveled. Of course the wheels wear down over time to so frequent riders will have to take new measurements at regular intervals.

[KobraX22] went with a QRB1114 sensor. It costs less than $2 and doesn’t require him to embed a magnet in the wheel like a hall effect sensor setup would have. It also shouldn’t interfere with any other fancy wheel hacks you’ve done, like adding a POV display.

[via Reddit]

17 thoughts on “A Longboard Speed And Distance Computer

    1. Cost, reliability, size considerations, update rate, lack of ownership of gps/smartphone, issues with calculating low speeds with GPS, fun? Many reasons for and against.

    2. I am friends with KobraX22. We don’t have a GPS to use so we would have to buy one that costs money. Smartphone GPSs aren’t very good either and aren’t very accurate or reliable for calculating speeds when we tried it (Even getting a GPS lock wasn’t consistent), not to mention the risk of damage in the event you bail.

      This also will mount onto the front of the board so it’s easy to glance at in the middle of a run.

        1. Using the QRB1114 is very cheap but very accurate! GPS takes a few seconds to minutes from cold start to get satellite info. I would of use a hall effect sensor with a magnet in the wheel (drill hole and insert magnet). The hall effect would make this even more robust, dirt, water proof. I guest he tested that it works with QRB1114 so using hall effect is sort of plug and play.

          I really like what he did. I wonder why I read 188km/h… that is 13298.261 rpm with a 75mm wheel!

  1. Cool project and nice work! I have to be a butt, but beyond the joy of making you can do this really cheaply and easily with a $20 bell bike computer. The wheel diameter calibration goes down to longboard sizes. Big advantages are you already have a moisture and vibration resistant device. Challenges are maintaining wheel balance after mounting the magnet, finding an epoxy to mount things that can resist that much vibration, and either shortening or storing the enameled wire.

    I was able to pull it off using an 1/8″ riser mounted on top of dropped through Randall IIs with the wire zip tied to the underside of the riser and the bikeputer base screwed and marine epoxied to the top.


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