• Description

We use an old-fashioned and very simple method for assessing bicycle chain wear. It is based on the idea that a bicycle chain works pretty efficiently until worn to the stage that it "stretches" by one percent (gets 1% longer than when new). This allows for significantly more use (wear) than more modern chain-checking devices, and it is assumed that you will replace your cassette at the same time as you replace your chain. (Not doing so will result in the chain slipping over the rear sprockets when under high pedalling loads). Leaving the chain to wear significantly beyond this stage will result in a rough drivetrain, and the high likelihood that you'll need to replace your chainring/s also when replacing your chain and cassette.

To see how much wear a chain has, use a ruler marked in inches. Bicycle chains use a half-inch pitch, so when you line one rivet up at the beginning of the ruler, there will be (with a new chain)  a rivet at each inch marking on the ruler (each second rivet on the chain).

As a chain wears, it gets slightly longer, due to looseness in each connection in the chain. A chain has "stretched" 1% in length when the rivet at 11 inches moves to be at 11 and 1/8 inches. (To be precise, that's 1.13% stretch).

Using this guide, you can see how much "life" a chain still has in it (or how long ago you should have replaced it!).