Danger: (thanks to buzz_kill): Attach it to your bike properly or you will kill someone! Ideas for xtra safe:
*Tape it with supertape or something like
*solder the led!
*Use superglue or hot glue gun to atach everything on its place
*Dont propel your bike witha a car (grabing a moving car so you get spped without peddaling)
Step 1: What You Need
*6 button cells (2 ligths up 1led, but 3 makes it more bright)
*2 leds (i used Green but you can use any led)
*Superglue or Hot glue gun (optional) (to attach it better)
Step 2: Make the Circuit
tape the cells and the switch together
Step 3: Put It on Your Bike and Done!!
Make another one and put it in the other whell
You are done!!!!