Seems to me that in order to organize/break up the start, you would need someone to step up and be the "organizer."
If everyone is riding the same route, then breaking up by average speed categories probably makes the most sense. But you'd want to make that plan clear in the emails because trying to tell a large group of people about it at the start will be difficult.
- Gray 2010 carbon WSD road bike, Rivet Independence saddle
- Red hardtail 26" aluminum mountain bike, Bontrager Evoke WSD saddle
- Royal blue 2018 aluminum gravel bike, Rivet Pearl saddle
Gone but not forgotten:
- Silver 2003 aluminum road bike
- Two awesome worn out Juliana saddles