Bicycle Chain Meter

thingiverse

This is a precision wear gauge. This device provides an accurate indication of how much your chain has elongated. If the chain links become too long, the teeth of the chain rings and sprockets will be worn down by the chain now rubbing metal on metal. There are numerous commercially available devices like this, usually made from high-quality materials. These devices typically work by inserting an angled slope until it can no longer fit or by turning a knob until it cannot be turned any further. However, depending on how hard you turn or push, the reading will vary. My goal was to create a chain tool that uses the exact same probing force every time. You simply press the two finger holes together until they make contact. To account for different materials and print tolerances, use a new chain to test where the needle points to. Remember this as your zero-line. Each line corresponds to approximately 0.2% of chain elongation. I replace my chains when they have become excessively long: 8-speed ~ 1.0%; 10-speed ~ 0.8%; 11-speed ~ 0.6%.