With the right tools and enough time, any bike lock can be cut, including cable bike locks. However, chain locks are some of the strongest locks you can but and offer a good deal of resistance to being cut. This is where a chain lock's Sold Secure rating comes in. The ratings are bronze, silver, gold, diamond pedal cycle and diamond powered cycle. Diamond powered rated locks are the most secure. Bronze chain locks, on the other hand, are less secure and are more about preventing opportunistic thefts.