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  1. #1
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    Reputation: cabbgage's Avatar
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    Seat post length

    I have a 400mm carbon seat post with only about 120mm above the frame. Is there an agreed amount that should be in the seat tube, so i can cut some off?

  2. #2
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    Reputation: rockyuphill's Avatar
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    Most frame manufacturers want at least 100mm of seat post in the seat tube to protect the frame and most seat post manufacturers want about 100mm of seat post in the frame to protect the seat post.
    I'm a member of NSMBA and IMBA Canada

  3. #3
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    Reputation: cabbgage's Avatar
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    Cheers, that will save me a few grams.

  4. #4
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    Reputation: phlegm's Avatar
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    Before you cut, just double-check to see if you can find the actual specs for both the frame and post.

  5. #5
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    Reputation: RS VR6's Avatar
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    The rule of thumb I "heard" is that as long as the post extends past the top tube...entire top tube...you should be ok.

  6. #6
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    Some bike Manufactures use a formula for calculating seatpost insertion. Ibis for example uses seatpost size 31.6mm X 2.50 = 79mm insertion. This formula doesn't really work for smaller seatpost sizes, but for the larger ones seems to work. I have run 79mm on a couple of Ibis frames for years with no issues.

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