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  1. #1
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    32.6 mm seatpost clamp

    I just finished a major rebuild on an older frame and the one part I cannot seem to get my hands on is a 32.6 mm seatpost clamp. I have performed hours of searching the net, to no avail. I spotted an older thread in this forum (with a less-specific subject line) in which the OP was facing the the same dilemma and unfortunately the suggestions there were no longer valid.

    Can anyone help me find this part?

    Many thanks in advance.

  2. #2
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    32.6 mm sound suspiciously like the diameter of the seatpost itself. The seatpost clamp must go around the frame's seattube, not the seatpost so it has to be a bit larger. Seatpost clamps typically come in 28.6 mm (1-1/8"), 30 mm, 31.8 mm (1-1/4") and 34.9 mm(1-3/8"). Measure your seattube's outside diameter and see if it matches one of these sizes.

  3. #3
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    Quote Originally Posted by HillRider View Post
    32.6 mm sound suspiciously like the diameter of the seatpost itself. The seatpost clamp must go around the frame's seattube, not the seatpost so it has to be a bit larger. Seatpost clamps typically come in 28.6 mm (1-1/8"), 30 mm, 31.8 mm (1-1/4") and 34.9 mm(1-3/8"). Measure your seattube's outside diameter and see if it matches one of these sizes.
    I think there was a typo here, the 1-1/4 size is usually rounded to 32mm or 31.8. If you have a 31.6mm seatpost you don't need to measure. The seat tube diameter has to be larger, so it's surely 1-3/8" (34.9 or 35mm). Note metric sizes vary because bicycle tube ODs are in imperial sizes, and the metric variation is the result of rounding differently.
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  4. #4
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    Quote Originally Posted by FBinNY View Post
    I think there was a typo here, the 1-1/4 size is usually rounded to 32mm or 31.8. If you have a 31.6mm seatpost you don't need to measure. The seat tube diameter has to be larger, so it's surely 1-3/8" (34.9 or 35mm). Note metric sizes vary because bicycle tube ODs are in imperial sizes, and the metric variation is the result of rounding differently.
    I also thought it might be a typo as 31.6 mm seatposts have become a new standard these days. However, seatposts being what they are, almost any size is possible.

    I was sure it wasn't the size seatpost clamp diameter that the OP needed and 34.9/35 mm is almost certainly the right one.

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  6. #6
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    OP here. 32.6 is what the mechanic (who is rebuilding my bike) told me. In any event, I have asked him to re-measure the exterior seat tube diameter with a caliper based upon the above comments. The frame is an aluminum 1996 Trek 8000, so who knows, it could be an odd size. I'm pretty sure that 32.6mm seat post collars do/did exist. If it helps, I do know that this is the seat post that I just purchased for it, and this post does fit my seat tube:

    Thomson Masterpiece 330mm Seatpost
    Item #: 50-2616-BLK-272

    https://www.performancebike.com/weba...mmaryOnly=true

  7. #7
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    Trek made the bike see if they have the replacement parts , ask via Trek dealer or Trek corp site.
    all else fails , get a larger one and shim for the differences.

  8. #8
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    For all practical purposes there are no odd sizes, though paint or powder coat could bring up a 1-1/4 to slightly over the nominal. You need a 1-1/4" collar or 32mm, or whatever they rounded it to. It's split and will accommodate the thick paint.
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