The Importance of Timely Bicycle Chain Replacement

Your bicycle’s chain is put through hell every time you ride. For every minute of pedalling, approximately 44,000 chain pieces are in motion, creating 320,000 separate instances of sliding surface friction.

And all of this is on a component that sits near to the ground and is exposed to the elements. As a chain wears, friction in the drivetrain increases, your shifting gets sloppier, and worst of all, you’ll quickly start wearing out other drivetrain components. So, changing your chain at the right time can save you money and make your riding more enjoyable. 

Basics of chain wear explained.

Over time, the chain’s pins and inner links will wear, and as a result, the pitch (length) of each link will grow. Because the chain’s overall length grows with wear, chain wear is commonly called ‘chain stretch’ – even though the metal does not (measurably) stretch.

Bicycle chain link - exploded view.
The standard pitch of a new chain link should sit at half an inch (12.7 mm), pin-to-pin. An inner plus an outer (wide and narrow) link of a chain makes an even inch. Chainrings and cassette cogs are designed with this pitch in mind, such that the chain rides at the base of the cog/ring when new.

As the chain pitch grows, it rolls higher on the tooth, accelerating cog wear until eventually it just skips over the top. And it’s this dreaded chain skip that you never want to feel when you’ve got all your weight loaded on a pedal.

Once the chain wears, the cassette and chainrings start to wear along with it, becoming ‘hooked’ from the high-riding chain. Replacing your chain before it wears too badly will dramatically increase the life of the rest of your drivetrain (cassette and chainrings).

A £40 chain every few months could save you hundreds by preserving your drivetrain.

New and worn chainring comparison .

When to replace a chain?

There is no exact science to knowing when to replace a chain. And there’s also plenty of debate about what classifies as a worn chain. However, the information in this, and following articles should get you as close to the answer as is known.

How long a chain will last will depend on your riding strength, your choice of chain lube, the chain, riding conditions, shifting habits and the terrain you ride.

Even when cost isn’t a factor, there’s far less risk of a broken chain in the heat of the moment, and it’s more efficient, too. Additionally, a worn chain will exhibit greater slack that leads to slower and sloppier shifting.

For the chainring, one test is to grab the chain where it sits on the chainring at a 3-o’clock position and pull hard. A worn chainring will likely let go of the chain and let it slip forward – proving just how dangerous such a combination can be.

Just be careful to test all of this in a controlled environment before heading into a bunch sprint.

Lifting worn chain off the chainring.If your chain lifts off the ring like this, it’s likely worn.

This ‘lift’ is possible because the chain’s pitch has lengthened and so no longer sits properly in the teeth. The photo below shows a brand-new chain. Chances are, if your chain lifts off more than our worn example, you’ll be needing more than a new chain.

However, do beware that worn chainrings can give a false reading with this method, and a new chain on a worn-out chainring will present similar lifting.

Lifting new chain off the chainring.As pictured, a new chain will hardly lift from the ring.

This argument for regular chain replacement is rather clear-cut if you’re riding on Shimano Dura-Ace, Campagnolo Super Record and SRAM Red components where the cogs can cost as much as an entry-level bike. However, the value proposition becomes a tougher debate if you ride on 105 or below, where replacement chainrings and cassettes are far more affordable.

Nevertheless, if you value crisp shifting, an efficient drivetrain, or if you often swap between wheelsets, then regularly replacing chains before they develop significant wear is a smart choice regardless of what your components cost.

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