It must be the color because in the pics the Z4 head tube looks higher than the Z6. It may be my view or due to different fork. I checked the head tubes and they were the same dimension. I guess I like the color better.

Kr32, I purchased a blue Madone with Ultegra and passed on the Grey with D/A to save money. I liked the bike but regretted purchasing the blue one.


Eidt: Sorry for not providing reassurance.