no you are supposed to use that to find a seatube that will fit you with an appropriate amount of post showing. Standover height is meaningless unless you are mountain biking since you will never be standing with both feet on the ground.

lemond himself reccomends you measure your inseam and multiply it by .67 to get the c-t seatube measurement.

49cm is way to small for you. You should be looking in the 51cm range.