Originally Posted by
gycho77
It was the same position. It's just a bad screenshot.
So same head position and others. That's why the yellow line is lower than the current head position.
You can tell by his ear position in relation to his shoulder that it isn't the same head position. (as well as that he's not even remotely looking up in the second one, while he's periscoping his head in the first)
His hip angle also decreases by ~ 5°, the opposite of what would happen by moving to shorter cranks if the position had stayed the same. The shoulder angle (bend at the elbow) decreases by ~8° as well, tightening everything up. This doesn't happen from 5mm crank length as the only change.
By dropping his head and rotating his hips he has dropped into a more aerodynamic position. Short cranks can indeed help with that SOMETIMES but too often someone jumps on the internet, reads 30 minutes on Slowtwitch and jumps to drastically shorter cranks... the same way time triallists 10 years ago thought you needed 180+mm cranks to produce more leverage.
Fwiw I think he has a good fit, and it looks aero. I just think the forest is getting lost in the trees a bit.