Chain checker readings vary like crazy between brands, which one is actually right?

Honestly, I keep seeing people at the shop trust any chain checker without thinking. Last week I measured the same chain with three different tools, a Park Tool CC-3.2, a Shimano TL-CN40, and a cheap no-name gauge. The Park said 0.5% worn, the Shimano said 0.75%, and the cheap one showed 1%. That's a huge difference for a part that costs $30 to replace versus a cassette that runs $80. How do you all pick which checker to rely on, or do you just eyeball the stretch against a ruler?

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park.abby22d ago

It's the same thing with tape measures at work, everyone has their favorite brand and they all disagree by a little bit. The ruler method is honestly the ground truth, but even then you gotta be careful about where you're measuring from. The real problem is these tools are built for different tolerances, so a cheap one might be using looser pins or softer metal that wears down over time. That's why I always keep a decent metal ruler in the shop bag, it's the only thing that's actually consistent. Chain checkers are fine for a quick guess, but when it matters, do the math yourself. Otherwise you're just paying for peace of mind, not accuracy.