I've been thinking about putting rollers on the wheels to power little dc generators, the rollers would attach to the brakes and would hit the wheels slightly before the brake pads, so if I just lightly tap my brake lever, I could make the light flash on one side for the front wheel, the other side for the back wheel, and those would be turn signals. Then if I acutally need to brake, when I squeeze the levers harder and both at the same time, the lights both come on and stay on until I release the brakes, and there are the brake lights. Keep in mind that this is just a concept idea and I have no idea if it is actually feasible, but I'm going to give it a try at some point.