Originally Posted by
RocThrower
I've read over and over again to size the bike by the top tube length, but the reach difference is only 3 mm between the 2 sizes
Be careful, Reach is not independent of Stack. Latter affects how former is measured (similar to how STA affects ETT). This issue comes up regularly in regards to the Domane b/c of the big jumps in stack height between its sizes (due to longer head tube), making the reach differences look small on paper. Reminds me of this horrible thread:
Long legs, short torso - Go go gadget legs