Wrap a long piece of NeoPixel strip throughout the grooves in the Carrera "foldable" helmet. Start at one back edge, shifting the strip so that four LEDs are visible to the rider along the front brim.
Cut the strip to length at the opposite back edge and tack the LED strip to the nylon webbing in the grooves of the helmet with a needle and clear thread. We didn't affix to every piece of webbing, just in enough spots to secure the LED strip.
Do not affix electronics to the outer smooth surface of your bike helmet! Helmets are designed to be smooth for your safety.