The following feature will be very helpful in keeping groups relatively together in fenced rides. Have the ability to tow yourself back to the group with a stronger rider. Both riders pair up and effectively behaves like a tandem. Sweeps can offer to tow stragglers, and stragglers also do not get a free ride either. Either one can choose to untangle at any time.
In a few group rides I’ve joined I’ve tried to sweep back a few slower riders. They already have to work quite hard if the sweeping people are putting out a lot of power.
What would help the most is for the ride leaders when they ask people to do for instance 1.5w/kg, have some limit the ride leader could use that prevents people going more than a certain speed. This would help for sweeping and prevent the issue of ride leaders having to sound like a broken-record pleading with the group to slow down.
Thanks. A fence serves the purpose that you mention. The ride leader is keeping the advertised pace. However, some newer riders do not understand positioning and hence they sit at the back of the group and usually gets distanced on descents. Before the gaps grow, a tow option would help the sweepers bring back these riders. An extreme version, being currently deployed, is to ask the sweepee to be on their coffee and the sweeps very really hard, at VO2 max efforts, to drag them along for 3 minutes. A tow would be a much more gentle thing and would also make the sweepee feel part of the chase.