Lemond figures seat height with this formula, most all the rest are very close:
SEAT HEIGHT (cm) = Inseam (cm) x .883
Set-up looks aggressive, it wouldn't hurt to flip it.
And 100k is a long ride for a new bike.
I also recommend a fit, depending on when you get it done, you can certainly try some things yourself. Flipping the stem and taking it easy might make a big difference.
Early Cannondales are said to be harsh, so that might have some effect as well.
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