GT sizing. Help?

[-=Mint_sauce=-]

As above, sorry for the seemingly idiotic question.

From what I can make out, my GT measures approx 15" from centre of top tube to centre of bottom bracket. maybe slightly over but certainly less than 15.5"

What size is it going to be?

(I know this sounds like a really stupid question, so please forgive my stupidity)

 

[drystonepaul]

Sounds like you've already correctly measured up your GT.
Centre of the BB to the centre of the top tube where it pierces the seat tube.
So if it measures 15 inches it'll be a 15 inch frame.

 

[SeeingisBelievingGTMuseum]

GT never built 15" frames so I'm guessing it's actually a 14.5 or 16". Time to draw the tape one more time and check it closely. (measure up the seat tube)