What is a typical differential proportion between 1RM for barbell and dumbbell variations of exercises?
I’ve just noticed that while I can barbell bench press 1.3x my body weight, I thought I’d try benching with dumbbells since all of the barbell benches were taken. I was quite surprised to find that I could barely do half that (in total, split between both hands). Actually only about 40% of my BW on the DBs in total.
What is the rough ratio generally, and what is the reason for this differential?