Are bike chains in Europe different? I tried to change the crank set on a bike brought over to the USA from Europe, assuming all bike chains were the same. The original chainring had 40 teeth and I wanted to try one with 44 teeth. The new chainring had a larger diameter as I expected, but I thought the separation of the teeth at the circumference would be the same. Well, I was wrong. The chain links simply didn't fit the spacing of the teeth on the chainring - after a half dozen teeth the chain was not sitting on teeth at all. Is there a difference between chains in the US and Europe?
There have been exceptions, like Dura Ace 10mm Track, but for the most part 1/2" chain pitch is totally universal. Pairing a heavily worn chain or chainring/cog with a new part can result in what you're seeing, though, because of the mismatch in pitch that develops as chains wear.