This is an age-old question. getting people to pull can be tricky though it doesn't have to be. In my experience, the more experienced the racer, the more likely they are to see the situation as it's developing and realize what they need to do to get back to the field. The problem is that many of your cohorts at that moment probably don't have a lot of experience.
So my suggestion is to talk loudly and try to cajole people into taking the necessary actions to turn into a cohesive pace line and chase down the field. if you seem as if you're trying to be constructive as opposed to being a jerk, I think people are more likely to help.
Iit could be as simple as loudly saying “hey! we could catch the field if we just worked together. let's work together let's just take 20-second pulls.” Or something like that. You want to convince them that if they don't catch the field as soon as possible, their race will be over.
And you roll to the front and start riding hard without attacking. You try to control them along the way. I think people like having someone else as captain of the group so long as it doesn't seem like the person is jerk or is just using them and looking to drop them.
If someone attacks the group you've created, yell out in annoyance, but don't attack the group. also, tell people that you don't wanna drop anyone on the hills, because lots of people are afraid of getting dropped on the hills. this is a practical suggestion as well, because if people are curtailing their efforts in fear of being attacked on the hill you won't go fast enough on the flats, and if you lose too many people on the hill you won't have enough people to finish chasing down the pack
The length of the pull depends on the group size. if there are two of you, the pulls need to be between 30 seconds to a minute long each. with six or more riders, yeah you can possibly do a rotating pace line. if there are disparities in strength, the stronger riders should pull longer not stronger.
