Originally Posted by
bartek.
Hmmmm haven't seen the Specs data (so maybe they also mentioned about it) but wondering how someone can judge -17 stem as more aero then any other value if not taking head tube angle in calculation?
That's because on road/track bikes, the headtube angles are within 2-3 degrees of each other, (72-74/75). So you're not going to be far off from perfectly horizontal with a -17 degree stem. Perfectly horizontal is the most aerodynamic stem set up. Deviate from this and it gets worse the more you go. Obviously of you have a 72* head tube, then -18 is going to be perfect, and 74* would need -16. As 73 degrees is right down the middle, this is what works best.