The Truth About Bike Chain Stretch: When Should You Replace Your Bike Chain?, by Cycle Maintenance Academy on YouTube. 12 min 44 s.
- Video length
- 12 min 44 s
- Time to do it
- 10 minutes
- Difficulty
- Easy
- Steps
- 8
What you need
Steps
Clean the chain with a rag so grit does not skew your reading. Spin the pedals backward to wipe the whole length.
Find out your drivetrain speed and brand. Check the chain, cassette or bike spec sheet for the number of speeds and the maker.
Look up the maker's wear limit. SRAM recommends replacing around 0.8 percent, while Shimano, KMC and Campagnolo each publish their own figures and methods.
Drop a chain checker into the chain with the tool's pins between the rollers. Push it down and read the wear scale where the tool sits.
If you have no checker, measure with a ruler. Line up the zero mark on a pin and check 12 inches of chain. A new chain reads 12 inches across 24 pins.
Compare the reading to the general limits. Modern 11, 12 and 13 speed setups often use 0.5 percent, many 5 to 10 speed systems use 0.75 percent, and some single speeds use 1 percent.
Replace the chain once it passes your maker's limit. A worn chain wears the cassette sprockets and chainrings, which cost far more to replace.
Check the chain again every few hundred kilometres, and more often in wet or gritty conditions.
Tips and common mistakes
A chain does not stretch like elastic. The rollers wear and the gaps grow, so the reading is about joint wear, not the metal pulling.
Different brands use different tools and limits, so follow your own maker's figure rather than a single universal number.
Replace the chain early. Letting it run past the limit wears the cassette teeth into a hooked shape that a new chain will skip on.
Measure in several spots around the chain, since wear is not always even.
Questions
What does 0.5 percent chain wear mean?
It means the chain has elongated by half a percent of its length. On a modern 11 or 12 speed drivetrain that is often the point to fit a new chain.
Can I ride a worn chain a bit longer?
You can, but the worn chain grinds down the cassette and chainrings. Replacing a cheap chain early is usually cheaper than a new cassette.
Do I need a special tool to check chain wear?
A chain checker is quickest, but a steel ruler works too. Measure 12 inches across 24 pins and compare with a new chain.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
