A lot of people will tell you just to get a new chain because they're cheap, but I like to clean them up a couple of times before I resort to replacing them. A lot of energy goes into making them, and it's a bit greener to use them for longer. On the other hand, don't use them for too long or they'll wear your cogs. You can measure the chain with a ruler (Google how) to see if it's worn. Just get some degreaser, citrus stuff works for me, soak it for a bit and then THOROUGHLY rinse and relube - not too much lube. On the other hand, a wipe down with a rag is sometimes all I need to shut the drivetrain up for a while...
A lot of people will tell you just to get a new chain because they're cheap, but I like to clean them up a couple of times before I resort to replacing them. A lot of energy goes into making them, and it's a bit greener to use them for longer. On the other hand, don't use them for too long or they'll wear your cogs. You can measure the chain with a ruler (Google how) to see if it's worn. Just get some degreaser, citrus stuff works for me, soak it for a bit and then THOROUGHLY rinse and relube - not too much lube. On the other hand, a wipe down with a rag is sometimes all I need to shut the drivetrain up for a while...