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O-ring bike chain wear limit

1,951 views · Published 11 June 2012 · 19:52 · Indexed 27 October 2026

Channel: theoverengineer · 2012 · Autos & Vehicles

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How can you reliably tell your chain has reached its wear limit length? Watch the calculation as I work with the 21-pin-distance and upscale it and relate it to the rear axle adjustment inside the swingarm.
On most bikes with 16/46T sprockets and a 118-link drive chain the wear limit length is a quarter inch more than the distance between the centers of the front and wheel sprockets when the chain is new. When this quarter inch is reached after repeated chain tensioning adjustments over time the chain has reached its wear limit length, seen at the swingarm reference lines. This new c-c +1/4 inch total distance represents a 1.5% elongation. Wearing the chain farther on is possible as there is room in the swingarms, to a max of 3.5% elongation, or a total of 1 inch.
As wear happens at the pins and they get thinner, the pins bend more under engine load and they might break. Wearing your chain beyond the 1.5% or 1/4 inch limit is dangerous if the bike is operated at full throttle or so acceleration or on extreme incline angles. I find that moderate riding around town even with some hills on a mediocre-powered bike does not snap the chain. This is a calculated risk which I do not recommend, much like riding with no tread lift on a tire. My bike reaches the 1.5% wear limit after about 8000 km (rains 9 months a year here), and reaches the end of adjustment in the swingarm (3.6% elongation) at 22-25,000km.
Same principles and design limits apply to cam and counterbalancer drive chains and chainsaw chains as well.

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