I went to REI yesterday because my bottom bracket was creaking. I brought my bike with me so I could get the right tools to take it off, but while I was there the mechanic actually took the crankshaft apart, cleaned, and lubed everything for me (I guess it was a slow day). He also checked my chain with a little gauge and said that it's more than 100% worn. He said that it is so worn out that my back set of sprockets could be damaged from it.
The mechanic said that I should replace my chain every 2000 miles. I have been using my current one for about 3000. Is 2000 miles a good distance to replace a chain? (I've never had this problem on my mountain bike. I always replace the chain every summer because of rusting. I didn't even know that it could actually wear itself out.)
I went home and ordered this chain on eBay. If I put it on my bike and my sprockets are indeed worn out will it wear out my new chain quickly? How will I know if I should replace the back COG?
PS: The chain I ordered has a Titanium coating, does that mean it will last longer than a "normal" chain, or is it just advertising? KMC says it can last "up to" 10k miles, is that true? Does anyone have any opinions of KMC chains?
Also, this is my first road bike, and I don't know too much about them. I got it for my birthday for commuting to school (and work in the summer).