Man you guys are cycle geeks.
But this is part of the "why"
I have titanium hubs... like a 935 (I think). If you built a whole Porsche like a high end road bike, it would weigh about 1500lb
The mountain biking was at least as good as expected - 2.5 hours on well constructed trails and pretty dry. I ditched the wife (her first time out, and she did really well) with about an hour to go and rode up the fire road to the top of the forest, then a 10 minute blast back down to the flat with my hands cramping up from braking. A high speed run back through one of the easy trails (twisty but flat singletrack) and we were off home.