There are several types of bike locks, including U-locks, チェーンロック, and so on. Let’s first distinguish them based on their meanings.
Chain Lock: A chain lock consists of a series of metal links chained, along with a lock head. It provides good flexibility and convenience to irregularly shaped objects.
U-Lock: Named for its U-shaped design, the U-lock is typically made of hardened steel and is difficult to break, making it suitable for use in high-risk materials.
Which lock is best? MAKE recommends two corresponding bike locks for your reference.

Chain Lock
Chain Lock: MK626, weighing 1.215 kg. It features alloy lock cylinder and ABS lock cover, 解凍防止およびアンチカット. Chain is wrapped by high-quality polypropylene soft fabric, これは抵抗力があり、耐摩耗性です, 防水性と防塵性. It is easy to wrap and move, allowing for flexible use. The mechanical key unlocking mechanism is convenient and fast.

U-Lock
U-Lock: MK625, weighing 1.1kg. It is made of zinc alloy and iron, making it sturdy and durable. ロックシャックルの表面を保護するシリコンカバー付き,優れた耐摩耗性と防水性能. The solid lock bolt provides anti-prying and anti-drilling protection. Its double opening mode increases the difficulty of theft. It uses a password lock with five-digit password, providing higher security.
要約すれば, you can compare the weight, unlocking method, and security features of these three products to find the ideal bike lock for your needs.