Road bike fitting: Fit calculator results look slightly different with the bike I am planning to purchase I am planning to purchase a Triban RC 120. My height is 181.3 cms and I am planning to get an L sized model.

Since I am new to road biking, after reading about it for a bit, I decided to get the bike fit done. I referred to this site to get the measurements: https://www.competitivecyclist.com/Store/catalog/fitCalculatorBike.jsp

The recommendations from the site and the actual measurements from the RC 120 are as mentioned below:



The top tube length looks okay to me. I am concerned about the Seat Tube Range params. Based on the measurements, I think my legs have a disproportionate length than the general standards. 

I am confused as to whether I should go ahead and purchase this or not?

PS: I am planning to rent a Triban 500 for a couple of days to get the actual experience of a road bike before purchasing one.
The frame you are planning to purchase has a sloping top tube. This means that the seat tube is shorter than what it would be if the top tube was horizontal, and you simply use longer seat post to compensate. 

On the other hand, the results from Competitive Cyclist calculator does not have any numbers for stack, or height measured from bottom bracket to top of headset. With horizontal top tube this is not a issue, because it is directly related to seat tube length, but with sloping top tube you have to calculate it from bottom bracket drop and head tube length. Since the fit calculator recommends an unusually tall frame, the head tube is probably fine, and if the handlebars are too low for you, it is easier to raise than to lower them.