I have done 100 miles before on a course with much more climbing. 6 of us rode for 80 miles as a group then I was solo last 20 when they dropped off but I ended at 5.50…… I’ve been ill recently for best part of 3 months so fitness is a bit off so I was guessing 6 1/2 hours.
I take the point ref faster riders having less to overtake, but surely in effect the fast riders at the front gradually getting slower leaves a big gap in the middle and theoretically the slower riders a the back means a gap in the middle lol