wow, completely dont know what happenned to me there, you are right mt bike frames dont come in metric, at least the ones i know of, thus, i do not know what size this is....in a road bike, that is my size, but my mt bike, not this one, my one im not selling, is a 17.5...i dont remember the frame size now, i might be able to get lester to measure it, do you know him? if so, perhaps u may want to view the biek at the same time to see if its compatible for you