I will show you how to make a bike sound like a musical box. you can use it as a replacement to a bell or just show off to your friends!It is really easy to make. You do not need any batteries, solar panels, electric generators...just pedal power!
when you ride the bike, the spokes will make a ding dong da noise. If you ride really fast then it will start to sound like a exhaust!
This is a slight copy of the turbospoke, http://www.ubergizmo.com/wp-content/uploads/2011/02/turbospoke.jpg
but it makes musical noises instead!