I am considering two different sizes of the same bike to purchase from bikesdirect.com and I want to make sure I have the right fit. However I am not of average proportions lol, so I am unclear whether to buy the XS or S size.
I'm 5'5", but have a longer torso and shorter legs. The XS has a more ideal seat tube length (though just barely at ZERO standover, but I can live with that), while the S offers a more preferable top tube length (with the downside being a negative standover clearance lol). Sheldon Brown says top tube length is more important than seat tube length, but I'm still unsure...
Should I go for the S or XS?
Here is the geometry sizing chart for the model in question:
so depending on the bike, you're probably best off looking at a 50cm frame. not sure how that translates to S/XS in the bike you're looking at. Based on the sizing chart for the bike you're looking at, I think the XS might be a smarter choice.
standover is pretty important because if you have to dismount in a hurry and your feet hit the ground something else might hit that top tube... just food for thought. Top tube is also important but there are more opportunities for adjustment. Example, you can easily make up the 1.5 cm difference in the top tube by getting a 1cm longer stem & adjusting your saddle .5 cm FWIW, you might be able to get it right just by adjusting the saddle.