The micro:bit on the front acts as a user interface. Between signals, it turns off the LEDs to save power. Push the A button to signal LEFT, B for RIGHT, and both buttons for STOP. When you do, it sends a radio signal to the back of the bike.
The module on the back (in a cute little guy housing) responds by displaying everything to the people behind you!
Make a robot friend with Adafruit’s CRICKIT – A Creative Robotics & Interactive Construction Kit. It’s an add-on to our popular Circuit Playground Express, FEATHER and other platforms to make and program robots with CircuitPython, MakeCode, and Arduino. Start controlling motors, servos, solenoids. You also get signal pins, capacitive touch sensors, a NeoPixel driver and amplified speaker output. It complements & extends your boards so you can still use all the goodies on the microcontroller, now you have a robotics playground as well.