I'm old now but I used to do repeats on Chesterfield hill-9% grade and .75 mile. I could only attack standing for about a quarter mile even at the peak of fitness. The next quarter mile I would spin in mid range gears and then stand again for about and eighth of a mile and then spin to about fifty yards from the top and then balls-to-the wall standing to the top. When I was 50 I was often among the first riders to crest the hills in the A-group on club rides. I was awesome. I still am actually but to humble to brag.