What chain or sprocket do I have?
For worn or unmarked parts: with a caliper and a tooth count, we tell you the chain size, whether it is American or European, and if it is time to replace it.
Measure the chain
All you need is a caliper.
From the left edge of one roller to the left edge of another roller 10 rollers away. Measuring 10 pitches is 10 times more accurate than measuring one.
Enter the measured length and the number of pitches to identify the chain.
Frequently asked questions
How can I tell an ANSI 40 chain from a European 08B?
Both have a 1/2" pitch, but the roller is different: 0.312" (7.92 mm) on ANSI 40 and 0.335" (8.51 mm) on 08B. Measure the roller with a caliper; that 0.6 mm difference is easy to see. On the sprocket, the difference shows up root to root.
Why measure the pitch over several links?
A 0.1 mm error on a single pitch is almost 1% of a 1/2" pitch. Measuring 10 pitches spreads the same error over 10 and makes the reading ten times more accurate. It also shows the real elongation of the chain.
When should a roller chain be replaced?
When it is stretched more than 2 to 3% over its nominal pitch. Beyond that the chain rides up the teeth, skips and wears the sprockets. Replace chain and sprockets together if the teeth are already hooked.
Why is the root measurement more reliable than the tips?
Tooth tips wear, and every manufacturer turns them to a slightly different diameter within the standard. The root barely wears and its size is fixed by the standard: pitch diameter minus roller diameter.