Description
The Shimano CN-HG40 chain is suitable for Shimano 7/8-speed gears as well as older 6-speed HG sprockets (18/21/24 speed gears). A Quick Link chain lock for easy connection is included.
The chain transmits the power from the chainring to the sprocket of the rear hub. It is exposed to extreme loads and weather conditions. Chains elongate at different rates depending on the conditions of use, but each one needs to be replaced sooner or later. Timely replacement of the chain is the only way to protect chainrings and sprockets from excessive wear. To get the best possible performance from the Shimano HyperDrive system, it is important to use genuine Shimano HG chains.
FITTING AND ADJUSTING TIPS
SIZING
How to measure your foot length
- Stand with the heel to a wall and put a measuring tape under your feet
- Read off the measured foot length in millimeters before your longest toe
- If you are between two sizes, choose the next higher, because feet are minimally greater under load
You can also use our template:
Download the foot measurement template
Birkenstock products are offered in European sizes. Please reference our Size and Width conversion charts below to determine your SA/UK size.
Your feet should be able to move freely without your toes hitting the edge of the footbed.

Before trying them on, put one hand under the toe and one under the heel, then flex the footbed a few times. This will initiate the break in period and will your help your new sandals feel comfy sooner.
Open all straps and step into the footbed. Close the straps comfortably, leaving enough space to allow your feet the freedom of movement. Exhale and enjoy.
For the first five or six times you wear your new footwear, limit the time to just a few hours. This allows your feet and body to gradually get used to the contoured arch support as well as the straps and buckles.