How do you tell frame size on a bike?

[boardsport311]

I have a Kona Fire Mountain that I am trying to sell on eBay, but I can't remember what the frame size is. I'm wondering if someone can tell me how to check on the bike and see what the frame size is? Thanks in advance.

 

[HowardSteele]

It used to be indicated on the seat post down tube, but with the frames no longer complying to the standard shapes, what with curvy top tubes and down tubes at various angles it seems that manufactures now specify sizes in small, medium and large. So taking your physical size, market your bike accordingly.

 

[aa9t8]

i believe it is the measure from the middle of the bottom bracket to the top of the seat tube.

 

[Bentriderlon]

i believe it is the measure from the middle of the bottom bracket to the top of the seat tube.

That's right. Sometimes it is also taken "centre to centre" but the difference is negligible.

Charles