In between drinking beer, eating chips, and watching Breaking Away today, I replaced the chain on my bike for the umpteenth time. The drive train on your bike is pretty expensive and it would cost a lot to replace the cogs, chainrings, and chain at the same time. Your drive train wears over time and eventually, you have to replace it. You can make your cogs and chainrings last a lot longer by replacing your chain on a regular basis.
Over time, your chain stretches. Well, it doesn’t actually stretch, but the pins and side plates wear a tiny amount. When you look at a single link the amount of wear isn’t much but it adds up over the length of an entire chain. You can see the difference when you line up two identical chains, one used and one brand new side by side. The used one will be longer.
If you ride a lot in wet or dusty conditions, your chain will wear faster because grit mixes with the oil to form a nice abrasive paste. If you ride with a worn chain, after a while, the teeth on your cogs develop a little hook near the top of their trailing edge. The more worn the chain, the more pronounced the hook becomes. As long as you don’t replace your chain, you won’t notice the wear on the cogs. But, when you put on a tight new chain, it will catch on the hooks. The effect is more obvious on the cogs that you use the most. At best a catching chain is annoying. At worst it can be dangerous because the chain can get jammed.
The solution? Replace your chain before it gets too severely worn. That means every 1000 to 1500 km to prevent your cogs and chainrings from wearing too badly. It’s much cheaper to replace your chain a few times a season than it is to replace your entire drive train.