Is this a high wear item on these bikes and do they have to be changed out often? What are the symptoms of a weakening tensioner? The topend of these bikes make so much noise I don't know what to attribute to "normal noise and what to excessive/loud noise. Has anyone actually changed their tensioner out and noticed an appreciable reduction in topend noise? A new one is $50 and I don't want to make an unnecessary purchase. Any help/personal experience would be appreciated. Thanks.