Cleanliness is next to Godliness

When it comes to bicycle chains anyway. A dirty and noisy chain is slowing you down, or making it harder to keep up with other riders with a well maintained chain.

As a rule of thumb, if you can hear the slightest noise coming from the chain area on your bike your chain is overdue for a clean and lube. Keeping your chain clean and oiled (don’t use oil) will extend the life of your chain.

Here's a Youtube clip showing how it's done.