First test done during a gran fondo this weekend: 160km with 2,500vm.
https://www.trainerroad.com/career/edouwens/rides/56054590-ochtendrit
My quark reads 5ish % higher than my Tacx Neo, so I have an ego inflating 235-240ish FTP on my bike using the Quark. 6h00 ride, av.power 140W, NP 185W (pushed hard on the hills, and rode the flats easy).
Nutrition went very weel, 2 bottles with Maurten 320 and some gels along with some more solid foods. Quite some stops though when waiting for all of the group to catch up. Was able to push north of FTP until the end, no cramps or excessive fatigue. Next week a similar hilly ride at 110mi with a smaller group so hopefully less stops and definitely aiming for a more consistent pace. Based on last weekend, an IF of .70 should be doable for les Trois Ballons.