Seatpost tolerance- Mtbr.com
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  1. #1
    Ahhh the pain....
    Reputation: Raybum's Avatar
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    Apr 2009
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    Seatpost tolerance

    building a new bike and have a tight seatpost problem. The frame manufacturer says the frame needs a 31.6mm post. When I measure my post, it's 1.245". I have another 31.6 post that unfortunately is too short, but it measures 1.241... so the question is, what is normal (or nominal) for a 31.6 post ? thus, is the frame undersized or is my seat post oversized ? Are there "standard" tolerances for seatposts ?

  2. #2
    mtbr member
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    You should be fine with the .023mm oversized seat post. That's like less than thickness of paper.

  3. #3
    mtbr member
    Reputation: borregokid's Avatar
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    manufacturing tolerances

    A bike shop with a seat post sizing "rod" could probably give you a better idea if it was the frame or the seatpost. My guess would be if you had a name brand seat post like a Thomson and it was too tight then it would be manufacturing tolerance on the part of the bike frame. If you have a high end frame and are dealing with a generic or low end post then I would suspect it would be the post. A quick trip to a bike shop should be able to answer your question.

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