Step 1: Parts List
Arduino Micro - You could also use Arduino Uno or any others, but they would have to be externally mounted to the bike. If you have a choice, get the version of the Micro without headers.
2x Pushbuttons - I used 12mm ones seen in the picture, and they work awesome.
2x RGB LED's - These need to be common anode to work with my code. I recommend 2, but the number is up to you. You should probably get more just in case.
Resistors - These are needed for the pushbuttons and the RGB LED's, so they will be specific to what you use. I used four 2k ohm resistors.
Batteries - Anything 6V or greater works but I will discuss this a lot more in the 'Custom Battery' step.
Wire - Lots and preferably thin and flexible.
Additionally if you want to waterproof the bars be sure to get some sugru. More on this in Step 7.