A properly sized chain keeps shifting crisp, protects your drivetrain, and helps your derailleur do its job. In this guide, you’ll learn how to measure bike chain size and set the correct bike chain length for your setup, so you can replace your bike chain with confidence.
Why chain length matters
Chain length plays a key role in shifting performance, drivetrain longevity, and overall derailleur function. Even though brands like Shimano sell chains in standard lengths, most installations still require sizing. Whenever you replace a chain, you need to set the exact number of links for your drivetrain. A chain that’s too short can overstretch the rear derailleur in the largest gear combination and may damage the derailleur or hanger. A chain that’s too long can lead to sloppy shifting, excess chain movement, and dropped chains.
WHAT YOU'LL NEED
Tools and materials
You only need a few things to size a bicycle chain.
- Your new bike chain
- Chain tool (pin extractor)
- Marker pen
- Tape measure (for XPLR and T-Type)
Got everything ready? Let’s get started!
How to measure a bicycle chain – Step-by-step guide
The correct chain length depends on the drivetrain manufacturer and the type of bike. You can determine the correct length in several ways.
METHOD 1
Count the links (comparative method)
Laying the new chain next to the old one and matching the length doesn’t work. A worn chain stretches over time, so using it as a direct reference will give you the wrong measurement. Instead, count the individual links on the old chain and cut the new chain to that same number. This method only works if the old chain was the correct length and shifted smoothly with your current drivetrain setup.
Pro tip: Count at least two or three times before shortening the new chain. Once you remove links, you can’t put them back.
METHOD 2
Shimano – Chainring-cassette method
This method works for all Shimano 11- and 12-speed chains.
- Shift to the smallest sprocket and the smallest chainring (if your bike has one).
- Place the chain over the largest sprocket and the largest chainring so the two chain ends meet behind the cassette (around the 11 o’clock position).
- Pull the chain tight and overlap the ends. The point where the inner plates of the overlapping chain end last sit on the chain is your zero position.
- From this zero position, add the required number of chain links plus your Quick Link to determine the correct chain length.
Road and gravel bikes
Road bike + chain with Quick Link: 2 to 3 links
Gravel bike + chain with Quick Link: 3 to 4 links
Road bike + chain with rivet pin: 3 to 4 links
Gravel bike + chain with rivet pin: 4 to 5 links
Mountain bikes
Hardtail + chain with Quick Link: 4 to 5 links
Hardtail + chain with rivet pin: 5 to 6 links
Full-suspension bike + chain with Quick Link: 5 to 6 links
Full-suspension bike + chain with rivet pin: 6 to 7 links
METHOD 3
SRAM 9 to 12-speed - Overlap method
This method works for SRAM 9- to 11-speed chains as well as SRAM AXS 12-speed Flattop chains.
- Shift to the smallest sprocket and the smallest chainring (if your bike has one).
- Place the chain - with Flattop chains, the flat side facing outward - over the largest sprocket and chainring so the two chain ends meet below the chainstay.
- Pull the chain ends tight so they overlap clearly.
- Starting at the overlap on the right side, add chain links depending on your drivetrain:
For 1x drivetrains: two inner links and two outer links
For 2x drivetrains: one inner link and one outer link
METHOD 4
SRAM XPLR & T-Type – Full Mount Chain Length Guide
For SRAM XPLR drivetrains on gravel bikes and T-Type drivetrains on mountain bikes:
- Measure the length of your chainstay with a tape measure - from the center of the crank axle to the center of the rear hub axle.
- Note the number of teeth on your chainring.
- Open the SRAM Full Mount Chain Length Guide online or in the SRAM AXS app.
- Enter your values and read the recommended chain length. For T-Type drivetrains, you can also enter your frame model instead.
Pro tip: SRAM chains typically come with 114 or 126 links (XPLR) or 126 links (T-Type) from the factory. Use the counting guide printed on the SRAM instructions to determine the correct length.
More tips for getting the chain length right
- On most modern rear derailleurs, you can release the tension or lock the cage, making it much easier to install the chain.
- No matter which method you use, always check the chain on a full-suspension bike with the suspension fully compressed.
- If you accidentally cut the chain too short, you can add links using a chain connector.
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