Originally Posted by
pitchpole
Here is what my rear cassette looks like, it is a pro-compe. I have put about 1900 miles on these gears since I bought it. I do not know how much the previous owner rode the bike. I replaced the chain a few times already I do ride in the rain.
http://www.flickr.com/photos/49331513@N05/
It's hard to tell without an unworn identical cassette to compare it to, but if you look at the shapes of the valleys on the larger cogs and compare them to the shapes of the valleys on the small cogs, it sure seems like the valleys on the larger cogs are ovalized.