A new chain is a minor expense; a new cassette and crankset are not. Investing in a simple chain checker tool can save you hundreds of dollars by alerting you when it’s time to shop. Chain Compatibility | Park Tool
For 11- or 12-speed systems, you should replace the chain when it reaches 0.5% stretch . For 9-speed systems or lower, you can usually wait until 0.75% . how to buy a bike chain
A 12-speed chain is significantly thinner than an 8-speed chain. Using a chain with the wrong width will result in it getting stuck between cogs or failing to shift entirely. A new chain is a minor expense; a
Pay attention to how the chain closes. Most modern chains use a "Master Link" or "PowerLock" (a tool-free connecting link), while some Shimano models still utilize a specific connecting pin that must be snapped off with pliers. 4. The Replacement Threshold For 9-speed systems or lower, you can usually wait until 0