8mm sterling silver bike chain bracelet size chart:

We recommend that you wear a bracelet 1cm - 1.5cm bigger than your wrist measurement. 

1. A bracelet is perfectly sized when you measure your wrist tightly and add ~1-1.5cm.

2. If you are between sizes, ask yourself how you like to wear your bracelet. If you wear it tightly choose the smaller size and if you like to wear it loosely take the next size up.

3. The most popular bracelet size is 19-20cm for men & 17-18cm for women.