When should the front sprocket and back cassette be replaced.I have a 2014 Trek 520 Touring bike with 6500 miles and am planning a cross country touring trip in August.

  • 2
    They should be replaced when they are worn out. Every serious cyclist should have a chain wear gauge. Your better bike shops have a wear gauge for sprockets, but a common test for the front is to see how far you can pull a relatively new chain off the sprocket. Generally chains are good for 2000-3000 miles, rear clusters about twice that, and front rings every 2-3 rear clusters. But a worn chain causes sprockets to wear much faster. Commented Apr 29, 2016 at 22:50
  • That assumes a clean drivetrain -- grit can chew through those things much quicker.
    – Batman
    Commented Apr 29, 2016 at 23:50
  • And most manufacturers say 900 - 1000 miles, for best performance.
    – zenbike
    Commented Apr 30, 2016 at 1:33
  • There are a number of similar questions with answers already written. Did you search the site before asking a new question? bicycles.stackexchange.com/questions/9122/…
    – zenbike
    Commented Apr 30, 2016 at 2:01
  • @zenbike -- 900-1000 miles for a cassette??? Maybe if you only ride on a sandy beach. Commented Apr 30, 2016 at 3:07


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