Originally Posted by
FBinNY
In a typical arrangement, the clamp goes around the frame's seat tube and compresses it onto the seat post. So, by now I suspect you've answered your own question, namely that the clamps are bought based on the frame, not the post diameter.
Yep. I had figured that is what the measurement is of. Wasn't sure so just wanted to reconfirm with a more knowledgeable individual.
On that note, mine measures 36.5mm, would it hurt to use a slightly smaller one? Smaller by ~4mm?