When we were on our race training rides in the 70's, we used to quite regularly come upon some guy riding at a good pace and we would get on his wheel paceline style. Then the competition was on. It was a test of wills and fitness to see who would drop off first. Or, some guy would come onto our paceline and do the same thing. Talk about pushing to the max, it was really incredibly tough but it was that needed push to get one over into the next stage of fitness. Ah, the good old days!