If you like or need to ride a bicycle on streets that are shared with automobiles, you can always be a danger to yourself, but what I fear most is other vehicles. This can be dangerous during the day, but add in reduced visibility at night, and things get even more complicated. Fortunately, there are some excellent lighting solutions available, and these DIY RGB wheel lights, which keep the light white in front and red in back, are some of the coolest that I’ve seen.
In this setup, 6 RGB LED modules are hooked up around the rim of each wheel. This made for even spacing on the 36 spokes. The lights are controlled via a central battery and controller unit keyed off of a hall effect sensor and neodymium magnet, similar to how most bike speedometers work. A Trinket Microcontroller is used for control, as its 5 IO points were convenient for the project.
The red and white setup indicates which way the bike is going, but one could in theory program this device to display whatever color pattern was desired. The source code is available here, and I’m sure the author would love if people were able to build on the original design!