There are several types of bike locks, including U-locks, reťazové zámky, and so on. Let’s first distinguish them based on their meanings.

Reťazový zámok: 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 bicykel locks for your reference.

Reťazový zámok
Reťazový zámok: MK626, weighing 1.215 kg. It features alloy lock cylinder and ABS lock cover, anti-drilling and anti-cutting. Chain is wrapped by high-quality polypropylene soft fabric, which is scratch-resistant and wear-resistant, vodotesné a prachotesné. Je ľahké ho zabaliť a presunúť, 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, vďaka čomu je pevný a odolný. Surface with silicone cover of lock shackle to protect,good wear and waterproof performance. 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.
V súhrne, you can compare the weight, unlocking method, and security features of these three products to find the ideal bike lock for your needs.