how do you know when a chain ring is too worn?
 

How do I know when a chain ring is too worn?
Some chain rings dont have square teeth to begin with and how do i know when normal rings are too worn?

2 pictures of a cassette/chain ring.
http://img651.imageshack.us/img651/2...c00649x.th.jpg
The cassette actually has a few teeth broken off which I assume makes it garbage, it skips i assume thats why

http://img402.imageshack.us/img402/2...00670cb.th.jpg
Its a Ritchey.
http://img402.imageshack.us/img402/1...00672sc.th.jpg
Same ring with a close up but the other is better focus

Skipping is a real good reason to think the chainring is worn to the replacement point and your picture of the crank seems to show many of the teeth are worn to a sharp point or noticably "hooked" so the rings are indeed ready for the dumpster. A cassette with truly broken teeth on one or more cogs is also DOA. When you replace them, be sure to buy a new chain also.

Out of curiosity, how many miles are on these items?

the freewheel (not a cassette) looks like it has worn teeth- but the teeth are not broken off. replace the chain too.

bah! how could you tell!?!?!
there are broken teeth but i didnt take a picture of them

Well that chain ring/crank is new to me so i have no idea. I was hoping it wasnt worn away since its all nice and light and stuff... dont some chain rings come like that?
but the 5-sp free wheel got about 8000 km last year easily... maybe 10 000 km and it was used when i got it

Sometimes there are shifting aids on front rings, but they don't quite look the same as the sharkfin pattern you have at least on the big ring. But there's certainly nothing wrong with the crank, just the rings.

It's in the teeth , look for rounded edges.. I just had to replace my rear cluster. Before it was changed, I had a constant problem with the chain falling off the smallest cog and getting jammed between the quick release and the cluster...

That sounds like more of a derailleur problem than a cassette problem... A properly set up derailleur wont let a chain fall off a cog. Your cassette would have to be worn down so much that there were hardly teeth left on it, for that to happen!

OP: time for a new freewheel and the two largest chainrings. If you can find out what the BCD (bolt center diameter) is, you can easily find new chain rings for it! The smallest ring looks fine, to me, but It probably wouldn't cost much more to replace that, too. The crank looks fine, just needs new chainrings.

Most of the time you just replace your chain and cassette/freewheel... if you do that and get a sort of whirry, throbby vibration with the same frequency as your chain speed under heavy load, your rings are shot too.

Another way to check is to see how far you can pull a fresh chain off the ring.

Big and middle rings are wasted. Granny ring's still good to go.
The freewheel cogs look OK, I'd probably look for a replacement though, since you say you're missing teeth.

yeah crazy. So if i just pick up a chain ring how do i know its bad?

Also chain rings are expensive!!! I had no idea
Its like a dollar a tooth!