In Reply To:
The front half cycles around well, the back hangs on.
This is a universal constant when it comes to high intensity training rides that involve riders with a diverse range of skills and abilitites. Nobody wants to get shelled off the back and for that reason riders will ignore obvious signs as they start pushing themselves beyond their limits but typically are not able to realize that they are in over their heads until it is too late. Other examples, the Tuesday night ride along the French Broad Riverriver in Asheville, NC is a pretty high intensity ride but is usually divided up into an "A", "B", & "C" ability group - wife and I rode with them last year after tkaing a 4-hour jaunt in the mountains that morning. The local Tuesday nighter here in my neck of the woods can be a real bear for someone who is not prepared for frequent bursts that can exceed 35-mph while competing with 60-65 mph traffic on a busy road near the downtown area. With a diverse field of riders (many racers from of all categories but can be just as many fast local roadies and the ride bears the untoward title "Death Ride" which is simply a historical reference that comes from the orginal days of the ride 25-30 years ago when particpants were known more for the complete lack of respect for traffic laws/lights/vehicular traffic than for the challenge of the ride. To the best of my knowledge, despite the rides name, nobody has ever actually been killed but there have been some pretty spectacular mishaps over the years.
¯\_(ツ)_/¯