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:

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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.

  • 1
    “as of 25.05.2018, CompetitiveCyclist is no longer available outside the U.S. due to GDPR regulations” can somebody post a screenshot? And where is the geometry data for the RC120? A size L for a 1.81m rider sounds too large (especially since it’s easier to make a small frame fit than the other way around).
    – Michael
    May 31, 2020 at 20:12

1 Answer 1


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.

  • Thanks for pointing out the difference between shorizontal and sloping tube. Read a few articles about it and could only find about stiffness and aesthetics. Can you please link me to an article which might talk about its effects on the rest of the measurements? Agreed on the other measurements. I guess its best to fit it right after purchasing it as you had mentioned. Strangely the seat post that I had seen on the bike was shorter. So I'll probably have to replace it anyways. I am interested to know more about bike fit in general. Do share any relevant links that might help. May 31, 2020 at 18:57
  • Uh, middle school geometry? Also, search term "stack and reach"
    – ojs
    May 31, 2020 at 19:17

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