Help me evaluate this cassette
 

When has a cassette worn out, or still just fine?

I've looked at Sheldon Brown's site, and for other info on the web, but I'm just not sure what I'm looking at.
What can you tell me about the health of this cassette? What are you looking for? Educate me, please!

http://home.comcast.net/~cccorlew/hosting/sprockets.jpg

http://home.comcast.net/~cccorlew/hosting/withchain.jpg

You can't tell much just by looking. The only sure test for worn out cogs is the installation of a new chain. If the chain skips on any of the cogs, when heavy pedaling pressure is applied, then those cogs are worn out. I would never trash a cassette until I give it the new chain test.

Just by looking, that second from largest cog looks quite worn. When worn, the U-shaped area gets longer.

It's hard to tell but the cogs you've shown us don't look worn out to me. Worn out cogs usually have teeth that are more pointed.
How far stretched is the chain?

Al

The chain is not stretched at all. At least according to my chain-checker tool (which I realize is a somewhat controversial device.)

the larger cogs on a cassette, like 26~34T tend to have a wider "U" section than smaller cogs.

to me, it looks fine.

If the chain has not stretched the cassette is probably OK.
It would be a good idea to measure the chain with a steel ruler. I like to measure two or three 12" intervals with a ruler and also check for roller/pin wear with a chain checker.

I just had a cassette I ordered arrive today. I've compared it as best as I can to the one installed and I can't see a difference. I guess I'll have one in the bank.

The one in the photo has near 10,000 miles on it, and I'm on my third chain.

I'll try the ruler technique, but I don't really trust my measuring and eyeballing technique....

I have my assistant (think wife) put pressure on a pedal while holding the rear wheel. This takes all slack out of the chain while I measure 24 link pins closely. A good steel ruler is needed for this. I replace chains by the time any 24 pin interval reaches 12 1/16th inches. Chains do not always wear evenly all the way around. I always get more than 5000 miles out of a good chain and I've never worn out a cassette (road bikes).