Always very happy to hear the words "I" and "set something up" in the same sentence!
It's always hard to cope with variations in ability and aspiration. By splitting the rides into two or three groups we've pretty much kept everyone on board through the winter, although some will have found the rides harder than others. There are riders who were shelled out the back last year who are now comfortable, having clearly done useful stuff to improve their fitness/endurance during 2012.
The unstated aim of the training rides is to ensure that - if you do them regularly through the winter and progress as
they progress (and for most people doing this requires that you do other training during the week) - you should be okay in 3rd/4th cat races come the start of the season, which is the kind of "base level" in road racing. I've no idea how this sits with the expectations of triathletes or people doing other stuff, but I assume they're making their own judgements on the value of it. There are stronger riders in amongst the regulars and, again, I assume they're doing their own stuff and making their own judgements about the value of the group rides.
End of chat, Kevin would say!