Critical Mass is a cycling event that takes place in cities around the world, where cyclists gather to ride together in a large group. The event aims to promote cycling as a sustainable mode of transportation and raise awareness about the rights of cyclists on the road. It typically occurs on the last Friday of each month and encourages participants to enjoy the ride while advocating for safer cycling conditions. The term "critical mass" also refers to the minimum amount of mass required to sustain a nuclear chain reaction. In this context, it is crucial for understanding nuclear physics and the behavior of materials under specific conditions. Both uses of the term highlight the importance of collective action, whether in cycling or scientific processes.