How are there millions of bike locks of the same model yet one key only unlocks one?

Question

How are there millions of bike locks of the same model yet one key only unlocks one?

In: Engineering

Answer 1

It depends on how the lock mechanism is setup

Say it has 5 tumblers with 7 pin lenghts there would be 7^5 combinations. There may be some mechanical limitations to the mechanism or methods that are used to make the lock harder to pick that reduce the number of practical combinations used (all the pins being the same or close in length would make the lock easier to pick)

If there were 1 million locks like I described above and 10,000 key combinations each possible key would open 100 of the locks.