On two oilheads with ~70K combined no failures yet, but it's always in the back of my mind. I bought BMW so that I would NOT have these types of failures. Lately, I've been re-thinking the simplicity of the chain. Chains typically don't just fail and leave you stranded. You get plenty of opportunity while cleaning and lubricating to inspect sprockets and chain for wear. If you don't take preventive action, then shame on you (or me!). Just MHO.