Originally Posted by
divtag
I am not very knowledgeable on bike geometry. I am 5'7 (when standing straight) and short legs, looking at the fit chart on the Salsa site I could go either way. Looking at the numbers, the big differences are:
Head Tube Length: 54 = 150 vs 55 = 165
Seat Tube Length: 54 = 490 vs 55 = 520
Standover: 54 = 754 vs 55 = 780
Now I have no clue what all of that means. Explanation?
The most important number for comparison is effective horizontal top tube length (Item B in the following). (Well, reach might be more important.)
http://salsacycles.com/bikes/vaya/
Indeed the Vaya "size" numbers are measurements of B.
Usually, bicycle "sizes" are the lengths of the seat tube and, because the top tube angle is different among bicycles, it's nearly useless for comparing sizes.
The 55 is 10 mm longer (horizontal top tube length) and 1 inch taller (stand over height).
As long as you have reasonable clearance, stand over doesn't matter too much. In my opinion, you should favor a smaller stand over height number the more angled the top tube is. The reason for this that people tend to straddle the bike more forward of the center of the top tube (where the stand over height is measured), which means the clearance will be
less than the number given.
I am 5'9'' and ride a bicycle (Rocky Mountain Sherpa 30) that has a very similar geometry to the Vaya. My bike is slightly smaller than the 55cm Vaya and I use a stem that is 10mm shorter than what came on the bike.
Given CCrew's and my experiences and being the same size, I'd suggest the 54cm over the 55cm.