If you replace your chain before its worn out, you will save significant money in the long run. If its left too late, you end up needing to replace the Cassette and Chainrings at the same time which ends up getting pretty expensive!
How do we know when? using a chain checker! we can do this for you anytime, or if you have one then get in the habit of using it.
It measures chain wear, a lot of people refer to this as chain stretch. Technically chains don't stretch, they are steel. The pivot wears out, causing more play and effectively makes the chain longer.
This places more wear on your other components, reduces shifting efficiency, just generally makes everything run poorly.
As a general rule, anything under .5 is considered ok or new, .5 up to .75 means its time to replace it. If you do it early enough it means you will spend $60-70 on a chain instead of hundreds on the whole set up. Basically pro-longing the life of your drive train.
To keep you chain in good working order here's a few tips, spend time it keep it clean, not just on the surface, get a decent product that helps to degrease it safely. Lean it thoroughly and dry it well, then apply a decent lube to it. There are only 3 types of lubes at this stage I would use here in NZ. 1- Rock and Roll Gold lube, this is actually a cleaner and lube and is brilliant. 2- Finishline Teflon Lube, stay away from anything synthetic. 3-If you really want to get the most out of it, Silca Chain Wax, this is a process but is extremely efficient.
How many times you need to clean it and lube it is determined by how much and where you ride. But remember, indoor trainers are extremely hard on bikes and chains in particular. So look after it on there as well!
