Only biking on the sidewalks? Even more important to wear a helmet there. Dangerous places, sidewalks, least for cycling. Yeah, helmets are a drag. But so are seat belts. Both tend to be uncomfortable and are a hassle. But both will save your life when you are least expecting it. That's the nature of most accident. They happen to the safest riding/driving people, and are never expected. For a cyclist, your head can, in the blink of an eyelash, become a flying object looking for a place to land. The helmet will soften the landing and hopefully protect your from becoming an invalid burden on your parents, or death. It's not all about you.