A clean chain shifts neatly, whereas a dirty one shifts sluggishly and wears expensive chunks out of the drivetrain. To find out how clean your chain needs to be, try reading the words stamped on the side plates. If they are legible, the chain is clean enough. If you can’t read them, the chain needs your attention. Ideally, clean your chain little and often – catching it frequently enough to only need a wipe-down. This is both the laziest and the best method – take advantage of this rare combination! Leave your chain dirty too long and you’ll need to look at the deep-clean section on the next page.
Laziest and best: a regular wipe-down
After a ride, lean your bike up against a wall and hold a clean, dry cloth or piece of kitchen towel around the bottom stretch of chain. Slowly pedal backward for 20 seconds, dragging the chain through the cloth. If it makes a big dirty streak, move to a clean bit of cloth and repeat. Job done. Simply do that every single time you ride and you maximize the chain’s life without ever undertaking a boring major clean.
You need to lubricate the chain occasionally as well, but note that you can do as much damage by overlubricating as underlubricating. Chains need a little oil, but no more than dressing for a salad. If the chain is squeaky, you’ve left it too long and the chain is gasping for lube. As a rough guide, oil the chain every 100 miles. If the chain collects greasy, black gunk as you ride, you are over-oiling. As above, wipe the chain with a clean cloth. Drip a drop of oil carefully onto each roller on the top surface of the bottom stretch of chain. (Drip oil is much better than spray. It goes where you want with little waste.) The important thing is to allow five minutes for the oil to soak in (have a cup of tea), then wipe off any excess with a clean rag – drag the chain through it again. Oil is sticky. Leave it on the outside surface of the chain to pick up dirt and it makes a super grinding paste.
Cleaning your chain little and often like this ensures that it never builds up a thick layer of dirt, which means that you don’t have to use harsh solvents on it. This is well worthwhile – cleaning agents, degreasers and detergent will all soak into the internals of the chain, stripping out lubrication from the vital interface between the insides of the roller. Each roller needs to be able to rotate freely on its rivet so that the roller can mesh neatly with the valleys between the teeth of sprockets and chainrings as you apply pressure. Wax lubricants are an alternative to conventional oils. Several manufacturers make versions that work in similar ways. The wax sticks to your chain, protecting it from the elements but providing a layer of lubrication. The wax is not as sticky as oil, so it’s less likely that dirt will adhere. But if it does, the surface of the wax will flake off, taking the dirt with it. New layers of wax can be laid over the top since the surface should stay clean, saving you from having to clean the chain. This system means that your chain stays dry too, avoiding oily streaks on your clothes and in your home. However, the system only really works if you start with a very clean chain – preferably a new one. A word of warning: never mix wax-based lubricants with normal ones – you end up with a sticky, slippery mess that adheres to everything except your chain.
Source : BIKE MAINTENANCE TIPS, TRICKS & TECHNIQUES
See also bike maintenance tips, tricks and techniques “Chains: what are they made of?”