Through a modular design, the front fixed base of the bike and the waterproof bag have been separated into individual components. This allows for carrying a dedicated inner bag and securing other items such as tents, sleeping bags, moisture-proof pads, clothing, etc. Features include waterproof performances with a water resistance of 4000MM, rolltop storage method, shock-absorbing and abrasion-resistant structure, and a multifunctional design with adjustable hung belt and shoulder belt.