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  1. #1
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    Fairly new cassettes is skipping....

    Howdy

    I replaced my chain recently... probably less than 300 miles ago. Last ride, I thought my rear der was bouncing between 12 and 13, as it wasn't shifting right to begin with... but then I started paying attention and realized NO... in fact, the chain is skipping over the teeth on my 12 cog.

    The cassette has maybe 1,000-1,200 miles. It is a Tiagra, but I didn't think the lower end cassettes were prone to wearing out too fast- I guess I would have thought the opposite, even. It's a 12-28

    This is the second chain on this cassette

    I have a 39/53 up front- I really don't spend much time in the 12 cog... even if the cassette was getting worn out, the 12 cog is about the last cog I would expect to blow out on me.

    What am I missing?

    Group is 6600, if it matters.

  2. #2
    Nigel nfmisso's Avatar
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    1st guess - high limit screw on the RD is a ¼ turn (or less) out of adjustment.
    Nigel
    Mechanical Design Engineer

  3. #3
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    New chain/old cassette is classic for skipping. The age numbers you give wouldn't normally have me expecting it, but it's possible, especially if you ride those smaller sprockets the majority of the time.

    One indicator of wear would be to measure your old for stretch (if you still have it). Another is to examine the sprocket itself and see if you see any undercutting or hooking of the back edges (where the rollers lean when pulling the sprocket).

    Often minor skipping resolves by itself as the new chain wears a bit and becomes more forgiving of the bad sprocket. You can get immediate relief by carefully grinding a bit off the top/rear corners of each tooth of the slipping sprocket.

    In the future, keep the chains properly oiled, and monitor their condition more closely. If they stretch much beyond 1/2%, don't replace them. It's probably too late for the cassette, and you might as well ride the pair together until about 2% stretch at which time you can toss the pair.

    BTW- it might not be classic new/old skipping, but misadjustment of the RD limit, or a misaligned hanger, or the shape of then inner plates of the new chain.
    FB
    Chain-L site

    An ounce of diagnosis is worth a pound of cure.

    “Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

    “One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

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