Old Skool here. My turbo bike has 52x11 for downhills with the big ring a Biopace. As my setup has a mean looking short cage 7 speed rear derailleur (105), the price I pay is that I am limited to 38x28 for climbing. But this is also the gearing of my Rossin road bike. Always 100% reality (up to 20% slopes on my Tacx Neo) as I like to think I'm training for riding outdoors and it's pretty hilly round here. Otherwise my take is that I might as well be on a spin bike. I've been debating with myself if I could eventually wangle it up that climb in Slovenia, I think yes, but there would be pain, lots of it, and it wouldn't be pretty or fast.