I have done a search and while there are a few threads that skirt around the edges of it, there doesn't seem to be one thread that focuses on how many k's you should expect out of a chain and/or what the variables are. I have heard a few stories about 15000-25000km for a sports bike chain. Is this reasonable for an O-ring chain assuming proper care and maintenance? I have also heard that the chain that comes on a brand new bike won't last as long because they use cheaper chains at the factory. Is this a myth? The reason I ask is that my CBR is up to 28000km on the factory new chain and it has reached the maximum adjustment mark to keep the chain at the correct tension. Is this a reasonable sort of life? Other factors I am curious about: - O-ring vs other chain types in regards to life of chain? - Any particular riding styles that may lessen the life on a chain? - And in preparation for buying new chain and sprockets, recommended brands if I don't mind spending some money. Given the fundamental importance of the chain/sprockets I figure that if I'm going to spend money on anything it should be chain/sprocket and tyres.