worn cassette or maybe not
 

I replaced the chain on my road bike with a 9 speed Sram chain with the power link. Since the old chain was on the borderline of needing to be changed according to the Park Tool chain checker, I thought that I could get away with not changing the cassette. First ride and there were several skips and I thought, "Oh well time to replace the cassette as well." I ordered a new cassette and continued my daily ride when the skipping stopped after two days. I'm thinking that possibly I hadn't fully engaged the power link (I did it by hand) and two days worth of riding engaged it. Or did the new chain wear the cassette into fitting since there was not that much wear? Any thoughts? Anyhow, at least now I have a new cassette to replace when needed.

I doubt the new chain would have worn the cogs that much in two days. Yes, the masterlink may have not been fully engaged initially. Or one of the links may have been stiff and riding loosened it. Also, there simply may have been some friction in the cable housing. Who knows? As long as it's working fine now, and your masterlink on your new chain is fully engaged, I wouldn't worry about it. Have fun!

Actually a slightly worn sprocket that's causing skipping with a new chain needs very little break in time to wear off the corners of the teeth that are the issue and run fine. If he skipping is sporatic enough that the rider can live with it, it'll get better. The problem is that the skipping is usually worse than people will tolerate even for an hour.

There's also a technique for manually fixing a problem sprocket, using a Dremel to grind a bit off the back top corner of each tooth on the problem sprocket. This is useful for an otherwise OK cassette that skips on one sprocket.

Agreed. I've also had cases where the new chain just skipped very intermittently on the old cassette/freewheel for one or two rides and then worked fine from then on.

I stand corrected. Good to know. Thanks!

Thanks everyone for the replies.