In this article I’m going to explain how to easily measure Shimano chain length.
I specifically bought a Shimano 6-speed chain to go with the Shimano freehub on my Koga Miyata Adventure. The obvious question when installing the chain is how to measure the correct length.
Let’s get started.
Methods for calculating Shimano chain length
There are various methods for calculating chain length, whether they are from Shimano or one of the various other brands out there.
Calculate Shimano chain length using old bike chain
Obviously the simplest method is just to take the same amount of links as the chain you took off. Don’t take the same length. A chain lengthens during its lifetime so you would end up with a couple of links less than the original chain.
Calculate Shimano chain length using sprocket, chainstay and chainring
You can also calculate the number of links you need based on the largest sprocket, largest chainring and chainstay length.
Calculate Shimano chain length based on chain tension
I’m going to use a little trick my LBS technician taught. There are several advantages to this method.
- When performed accurately it’s much faster than the other methods
- You don’t need the old chain, which may come in handy when you don’t have it anymore.
Step 1. Chain placement
First you need to place the chain on both the smallest sprocket and smallest chainring.
Step 2. Finding the correct chain tension
The idea is to put a little tension on the chain so there’s a straight line between the lower jockey wheel and the place where the chain comes of the smallest chainring.
The chain should be able to move freely and not be rattling along the top jockey wheel. The angle between the the jockey bolts is about 15 degrees and the chain is about level with the ground.
Step 3. Breaking the chain
With the chain tensioned this way running along the smallest sprocket and smallest chainring, no matter what gear you’re running, you’re always going to put more tension on the chain.
So with one hand hold the last link and the other having some chain slack, you know the exact spot where you should break the chain.
And that’s how you easily measure Shimano chain length! If you like this article give it a thumbs up. If you have any questions or suggestions for new articles, let me know in the comments below. Cheers.