This is a really easy weekend project that you can do to give your bike some brake lights.
Step 1: Get Your Parts
Get the parts that are needed:
Lots of Zip-ties
Copper (I used some 14 gauge Romex I had around my house)
Tail light (I used a Planet Bike Blinky 3 that I have been using for years on my bike)
Step 2: Take Your Stuff Apart
Take apart your tail light. We are needing inside in order to rewire it to work with your brakes.
Step 3: Bend Switches for Your Brakes
Take your Romex and bend it into a switch that you can zip-tie to your brakes. Solder one end of your wire to the end of your Romex.
Step 4: Zip-Tie Your Switches to Your Bike
Take your newly soldered switches and zip-tie it to your bike. I have disc brakes on my bike, if you have a different style of breaks I'm sure that a quick re-work will suffice.
Step 5: Re-wire the Tail Light
Take the battery connector closest to the power button (we are going to be running our wires through here later) and cut it in the middle. This is where we are going to add our wires from our switches.
Step 6: Zip-Tie Everything Up and Attach It to Your Bike
Zip-tie your wires to your break lines and make sure to leave enough room that you can turn your handlebars right and left without it catching on your wires. Test it out and make sure that everything is working as it should.