Road is entirely different, you are not managing with sideways fall-off, gravel, rocks and ruts. It really sucks it out of your legs..my legs anyway.
After dropping my stem a few spacers I did get 2:30 min done spinning up what seems to be about a 15% grade this morning, in a straight line. But that was at my limit. I'm thinking I need one lower gear, and 40 year younger legs. Pretty happy it was not cardio failure, just muscle failure.
I think I am going to practice this twice a week; practice makes perfect... and I have lots of room for improvement.