Hi all!
I am hoping this is the right subreddit to ask a bike sizing question in but if not, please let me know! I am looking to purchase a Lauf Seigla in the coming months but find myself stuck on what size to get. I am 5'11" with a 33" inseam (or just slightly under both of those, little hard to measure by oneself) which puts me solidly at the top of the medium seigla. However, if I compare my current bike frame (which I have gotten a bike fit on), that geometry much more closely matches a size small seigla.
Correct me if I'm am wrong, but because my current bike I am comparing to is a road bike (Caad 13, size 54), I am not comparing apples to apples in terms of frame geometry since the seigla uses a longer top tube with a shorter stem, messing with simply comparing reach figures for the two frames, right? Per my bike fit, I know I should be targeting a saddle height of 75.8cm, saddle setback (to nose of saddle) of 9.8cm, and an ultimate reach figure (saddle tip to brake hood tip) of 74.5cm. When putting all these numbers together and doing some math, I think a size medium seigla with a 90mm stem gets me in the same fit area but I am really having a hard time reading geometry charts and trying to compare this stuff.
So, my ask to you fellow bike friends is this: Have I deduced correctly I should go with a size medium and swap the stem from stock to 90mm (10mm increase) or can some of you who can read geometry charts better than I set me on the right path? I plan to use this bike for gravel races so if a size recommendation may be based on fit, I will be going more aggressive but not all out, I am not pro levels of flexible haha.
I appreciate any help you can give!
Seigla geometry page: https://www.laufcycles.com/product/seigla-rigid
Caad 13 geometry page: https://www.cannondale.com/en-us/bikes/road/race/caad13/caad13-disc-rival
by gthivier