I've been riding women's group rides for years so here is my 2cents. Mixed group rides with a and b groups can work - but usually they work better when you have large groups, and the way people have described rides above is always a good thing so that people know what they are coming for.

I would recommend that you do most rides like the ones above - i.e split into two groups, but ask that those groups each have a ride leader and that if people get ahead, they regroup. i.e. both groups do not stay together, but they regroup as group 1 and 2 so that those groups stay together. All these things need to be stated at the beginning of the ride; if the ride leader is continually chasing one or two people, they need to ask them to either abide by the rules or ride by themselves.

The other thing that is really good and supportive for all is to have at least one ride a month and more often if you can with a good ride leader. This one is a no drop ride - Usually, I keep these rides together in a double paceline kind of idea, teaching people how to ride close together, etc. the better riders are there to teach the not so experienced riders. I try to do these on wide, not too hilly routes. If there are hills, I let the riders climb at their own speed, but when they hit the top of the hill, they either turn around and escort riders back up or stop and wait and regroup.

spoke