Monitoring chain wear is only half of a proper drivetrain maintenance plan. Cassettes and chainrings wear too—and replacing chains without checking sprocket condition is a reliable way to shorten the life of new components.
The Unior 1658/2P Sprocket Wear Indicator provides a simple, repeatable method for determining whether a cassette is still serviceable or ready for replacement.
The tool consists of a chrome-plated steel bar permanently attached to a short length of chain. To use it, drape the chain over a sprocket, ensuring the tip of the steel bar rests in the valley between two teeth. The final chain link should hang free and not contact the cog. Apply a 10 Nm force to the end of the bar and attempt to press the last chain link down into the tooth valley.
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If the link drops in easily, the sprocket is still within acceptable wear limits.
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If it resists and will not seat, the cassette (or chainring) has reached the end of its service life.
This tool removes guesswork from drivetrain assessments and helps prevent premature chain wear caused by worn sprockets.
Key Features
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Accurately checks cassette and chainring wear
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Helps prevent premature drivetrain replacement
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Chrome-plated steel construction for durability
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Simple, repeatable 10 Nm test method
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Ideal for professional and home mechanics alike
