I have a feeling the answer to this question is the same one I get when I ask about to know if you need to replace your cleats: "Oh, you'll know."

But seriously, how often do you guys swap out old for new chains? What do you base this decision on? Is there a mileage zone that exists where it's "a good idea" to change your chain, like oil in gas tanks?

Also, I know it's been done in many a thread, but if anyone wants to throw in some new 1/8 chain recommendations, that'd be cool. I was/am riding an Izumi ESH but want to go cheaper.