Bicycle Mechanics - Chain & Freewheel Life

Five months ago I bought a Trek 7.2fx and have ridden it 1600+ miles. The other day I brought it to the bike shop and he told me that chains have a 1600 mile life expectancy because they stretch and grind down the freewheel and will eventually damage my crank gears. I was hoping you wise posters of the Mechanic's forum could confirm this for me, because 1600mi doesn't seem like that much. Should I quickly get new parts she dies?
Thanks!
Jeff-

I have 3,000 miles on my chain and cassette, and everything is still running flawlessly.

depends on a lot of factors, from what kind of chain, what kind of lube, where you ride, etc.

Just judging by the type of bike you have, I am guessing you are riding a combination of paved bike paths, sidewalks, neighborhood streets and packed gravel hike & bike trails, and you're not putting a ton of torque on it, riding creek crossings or in the rain or mud. I would also guess you have never lubed the chain, or if you have, maybe not with a legit bike chain lube.

If those assumptions are close to correct, then I'd say, yes the chain probably is ready to go at 1500 miles. No it's not likely to put the hurt on the chain rings or cassette since those are all steel and you are not riding real hard.

Now if you want to save money on chains in the long run, here's the routine: Buy a SRAM PC69 chain and a bottle of Rock & Roll Gold or other highish-end chain lube (Pedro's Ice Wax, maybe my favorite Maxima Chain Wax, etc.). Faithfully lube the new chain once a week or every 100 miles and you will probably get 3-5K out of the next chain. Invest in one of those chain cleaning machines from Pedro's or Park Tool and a bottle of Simple Green, and about every month or so (400-500 miles) clean the chain with the chain machine and Simple Green, then let it dry overnight and re-lube it. You'll get max life out of the chain and if you don't ride in the same gear all the time, probably sell the bike with the original cassette and chain rings still in working order.

If you neglect it, maybe replace it with a cheap chain and put WD-40 on it only when it has visible rust, then sooner rather than later it will start to ghost shift and skip and make noise and generally drive you nuts until you quit riding.

The other thing you can do is a visual inspection. If you hold a ruler along the chain, with the zero mark aligned at one of the pins, the pin at 12 inches (24 links away) should be within 1/16" of the 12" mark. It if is more, the chain needs to be replaces. The other thing is to look carefully at the cogs and chainrings. The tooth shape should still be symmetrical. If they start to look like a shark's tooth, its time to change the cogs. Always be sure to get a new chain when you get new cogs or chainrings, otherwise you'll just ruin the new cogs in a short time.

Thanks for the helpful responses!

I pick up most of my miles on bike trails, main streets and highways commuting, and I generally bike in all weather since my it's my only mode of transportation. I actually lube my chain quite often and had been using some sort of chain lube(i don't remember which brand, it's the kind my bike shop uses) until I ran out and started using 3 in 1 oil(is that a good lubricant to use?). I will look into the long run chain saving techniques, but I am a poor college student and probably cannot afford it in the short term.

The teeth on the cogs are shark tooth shaped and worn down, so I should get a new one. Are they all pretty much the same, or are there better parts I should be buying?

And also, I plan on biking through the winter-- last year the snow only stopped me when it was 10+ inches. Should that have any effect on what I purchase?

Thanks!
Jeff-!

Probably the biggest factor is what cogs you run in the most on the back. That and how dirty it is where you ride.