santa cruz seems to be going against the conventional wisdom here - the flat bar and drop bar skitch have the same frame. same geometry. they do skew the height recommendations a bit, since the hoods on the drop bar bikes are so much further forward than the grips on the flat bar bike :
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this is probably extra important because the reach on these bikes seems VERY LONG. at 6’2, they recommend the XL for me, with 435 mm reach. my creo was 391, my aethos 402, my addict 384. 435 is nuts.
as far as i know, most other bikes which offer both bars have slightly different frames, like the diverge. maybe because the reach is so long, it works OK with the less extended flat bars, and they just side down for drop bar riders. that’s what the chart implies.