It took me about 1 minute, and after all it's just a school project. They can learn just as much about business trying to bring a doomed product to market as a they can with a good one. Probably more, actually

How about a helmet with a small loop of cable hanging off the back that you could pass a U-lock or a cable lock through? There, there's your idea. I don't have time to bring that one to market, you can have it. You're welcome!