Do modern bike helmets that prioritize aerodynamics and ventilation over traditional impact-absorbing materials truly address the issue of safety and security in urban areas, where collisions with vehicles and other hazards are more likely to occur at lower speeds, or are manufacturers prioritizing performance over protection, leaving cyclists vulnerable to serious head injuries in the event of an accident, and what role do certifications like Snell and CPSC play in ensuring these helmets meet minimum safety standards in real-world scenarios?