This unique speedometer uses a GPS for speed tracking, and displays your speed with an RGB LED. While as-programmed the speed is displayed only as stopped (red), +2MPH (yellow), +9MPH (blue), or +13MPH (green), this could be expanded to a more granular form if you so desire. Also, the GPS unit could be used to show other stats, like how far you are from home, and the bike has a white flashing mode specifically for night visibility.

Step 1: What You'll Need

For this project, you'll need

RGB LED
Arduino Pro Mini (Amazon)
GPS module (Amazon)
LiPo Battery
Switch
Button
Charging module (I used something like Edition 1 with a micro connector, but I'd recommend Edition 2 instead, listed here (Amazon) if it will fit)
PLA
Hot Glue
Zip ties

*Note that the charging module is not shown in the diagram, but will go between the Li-Po and Arduino Pro mini

Step 2: Print, Solder, Stuff

Print files are available here. Top is printed with "Clear" PLA (Amazon) to let light shine through.

Solder per schematic in previous step + Li-Po charger.

Everything will be a tight fit, and you'll need to secure buttons and charger as seen in the video. Also, feed zip ties through the four rectangular holes toward the middle to facilitate handlebar installation later.

Step 3: Program

Load the program found here using a USB-TTL converter. I used this one (Amazon), which is kind of expensive, but seems that many of the cheaper ones are necessarily compatible with Windows 10.

Step 4: Install and Use!

Wrap zip-ties around your handlebars, turn it on with the button on the bottom and start riding. It may take some time for the GPS to get a good lock on satellites, but after this, you'll be able to look down for an instant to see what speed mark you're at, or provide lighting.

If you enjoyed this project, please consider voting for it in instructables Arduino Contest 2019!

More background on this project and using a GPS module with Arduino can be found in this article.

Note links to Amazon are affiliate.