This is a repost from the Road Cycling forum... Today it happened again.. Steep uphill and I moved past everybody and attacked out of the saddle. I was getting into a great rythm... Then clank.. Ihe chain skips, puts my cadence and my thinking out of whack and I am in too high of a gear and I mash up feeling ever pedal stroke inch the biek forward... I could distinctly feel the cahin skip in the front chain rings.. Is this is a worn chain or crank issue... The whole bike has approx 700 miles on it...I was not cross chaining, I was in the 39-15.. Triple chainring with a 12-25 cassette..

BTW Here is another post a while back which I thought that my front chainring was worn but people pointed out that it was shifting reasons...

http://www.bikeforums.net/showthrea...neven+chainring


Thanks,
-AJ

Something similar happened to me a few months ago, and it turned out to be a stiff link. The nice gent at my LBS waggled it back and forth for a few minutes, and I was good to go. (That may or may not have been the correct thing to do, but my bike is a cheap piece of crap, and he knew it, so I doubt he was going to suggest replacing the chain, or anything expensive.)

Check for chain stretch with Park Tools chain wear indicator. If it measures .75 replace the chain. If it reads 1.0 then it is a really good possibility that you May need to replace the chainring as well. Your chain should not skip under any condition. Just finished dealing with this problem yesterday. Good luck!