Thanks for the answer Pleiades.

Yeas thats what I thought too, its a little strange indeed. I have been driving through Kazakhstan, Kyrgizstan, China etc and can definetively say that there has been some sandy stretches, gravel roads, dusty sections etc. And I havent cleaned the chain and sprockets along the road either. Which I am suposed to do I guess....have been spraying the chain quite often though.
So maybe some of the answer lies there.

Anyhow - 30-35 k km, is that a normal lifespan on a sprocket?

Would you have changed only the rear sprocket or would you have changed the chain as well?

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