As I understand it, the Z5 has a carbon frame, while the Z85 has an aluminum frame. These are two different animals, altogether. Just decide if you'd prefer CF or aluminum.
IMHO, the CF is the better value money wise, but it might also be the biggest PITA, in terms of practical convenience. OTOH, CF just might provide the heavenly ride for which you'd always been searching, and well worth any other sacrifice. Have you ever cycled on carbon? Do you have any idea what it feels like?
Aluminum is a simple puzzle to solve. You can take it to the library and lock it up at the bike rack without worrying about some idiot scratching up your bike, just to more easily remove his own. You can go to McDonald's or Pizza Hut, lock it up at the parking meter, without worrying about it getting scratched or stolen. Scratched steel or aluminum is a much easier fix, than carbon fiber. A force causing a dent in the frame of steel or aluminum, can possibly translate as a crack in carbon fiber. Carbon fiber can easily conceal cracks in its fiber. You can crash or take a spill on your aluminum or steel bike, with little worry about subsequent crashes. You've just got to be concerned about the integrity of a CF frame, after a crash. Your next crash, just might be your last!
Like I always say...
If you can afford to lose a CF bike without much worry, then you can afford a CF bike. If you can't, then you're in the wrong arena.
Last edited by WestPablo; 05-10-14 at 02:54 PM.