LED Unicycle

I’ve been making LED rings for my unicycle since 2013. Instead of attaching an LED strip along the inner wall of the rim, I decided that the LEDs should point outward for the best side visibility.

The first prototype was made out of an LPD8806 strip that I cut between every two pixels and soldered into a circle. I then painfully pushed it through a heat shrink tube to protect it. This design had two rings, one for each side of the rim.

The first approach worked pretty well, but the rings were fragile with so many rigid solder joints and I was constantly having to slice the heat shrink open to repair cracked connections. I decided to design a slightly smaller rigid double sided PCB ring that can live just inside the rim.

The second iteration shown above is a 5 segment ring with 60 WS2812 pixels per side. I designed one section to hold all of the controller-related stuff. This version used a teensy 3.1 microcontroller, SD card adapteradafruit 9-dof breakout, and a mic for audio reactivity. It ended up not being a good place for a microphone because I pretty quickly kicked it and broke it off.


I then decided to integrate all of the electronics into the ring between the LEDs. This version was designed to have an atmega32u4 microcontroller, battery charger, boost converter, IR receiver, bluetoothLE, mpu6050 IMU. Not long after I finished this version, APA102 LEDs became available and they’re able to be updated much faster so I redesigned it again to use them instead.

Sarah Smith Coasting - Photo by Brian Oley

Sarah Smith Coasting - Photo by Brian Oley