Know How

The how to replace a chain and find the right chain length on a road bike

19.07.2019
by Christoph Bayer, Manuel Buck

Every watt your legs churn out needs to be transferred to the rear wheel: that’s where your chain comes into the picture. But this core component is under constant strain. It gets yanked, stretched, pulled and carelessly thrown over the sprockets. This constant abuse combined with adverse conditions lead to wear and tear. In this tutorial we’ll explain how to replace a worn-out chain and how to determine the correct length for your new one.

If you don’t replace your chain in time, it will being to wear and damage your cassette and chainrings at an ever increasing rate. Staying on top of maintenance and replacing a chain is a lot cheaper than replacing your whole drivetrain!It’s important that you regularly check the length of your chain and replace it when needed. Tip: get yourself a chain-gauge! Many manufacturers offer them for under € 20.

If you don’t have a chain gauge at hand you can use a conventional ruler. With a new chain, place the 0 of your ruler on any of the pins and on a fresh chain, another pin should sit at exactly 254mm. If this measures 256mm or more, the chain is worn-out and must be replaced.

Yikes! A poorly maintained chain means bad shifting performance and will quickly wear-out the rest of your drivetrain. Metal on metal sucks!

Difficulty

  • Easy

Required tools

  • Chain tool
  • Quick-link remover or pliers if needed
  • Power lock pliers
  • Chain gauge (to check the chain)

Instructions

There’s a wide range of chain gauges on the market. This handy tool will help you determine the wear of your chain.

Split your old chain with a chain tool and remove it from the drivetrain – if you don’t have a quick-link on your chain use a chain tool and remove one of the pins.

If your chain comes with a quick-link, you can remove this either with a quick-link tool or needle nose pliers.

Now pull the new chain over the big chainring and largest sprocket without threading it through the rear derailleur. This little trick helps you determine the correct length for your new chain.

There are different opinions and approaches regarding the ideal chain length. SRAM recommends splitting the chain with an overlap of two chain links and 3 pins. It’s clearly marked here with an arrow.
Remove the excess links with a chain tool. Make sure you remove the right pin otherwise the ends won’t match up. Take note! The procedure is different depending on whether you use a quick link or a rivet pin.

Now thread the chain over the sprocket and through the jockey wheels on the rear-derailleur.

Using a quick link is the most efficient way to join a chain. Note that 10 and 11 speed quick links can’t be reused, and that SRAM’s Power Link is marked with a direction marker.
Joining a chain with a quick-link is dead easy. Install the quick-link by hand and position it to the top of the chain.
Pull the rear brake and put some pressure on the pedal until you hear a clicking noise – the quick-link snaps into place!

Tips & tricks:

  • Unlike SRAM chains, Shimano chains usually have a running direction
  • If you use a quick-link make sure you put it the right way round (direction marker)
  • Quick-links can only be used once

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Words: Christoph Bayer, Manuel Buck Photos: Valentin Rühl

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