Unfortunately, 3767/4000 GranFondo cyclists did not make the same effort to mind the convention of cycling, nor to mind their safety or the safety of those around them. Basically, they all rode bikes like car2go drivers drive. In a word, it was mayhem. Total mayhem.
Brandon, doing the longer distance ride, started about an hour ahead of the pack with what I would assume were experienced athletes. I don't think he'd disagree, and from his account I think the first 30 km or so of his ride (the "pro" part) worked very well for him. He hit 78.5kph in some well orchestrated downhill drafting which is both impressive and a testament to how a well executed group-ride pack (I refuse to use that "peloton" word, this isn't the France Tour) can make you very very fast.
I had to start at the back of all the rest because of two false starts due to flat tires and broken presta-valves. That meant that by the time I was 4 km in I was rocking past people riding the road bike equivalent of beach cruisers and the seemingly never ending 6 abreast "cycling clubs" that are really nothing more than WASPs with nothing but extra money to burn on bikes and all the time in the world to spend socializing while blocking everyone else's way.
Brandon's group, after their 30km extension loop, actually tailed on to this same group of the least experienced riders. He was in the same boat as I, if even worse because he was faster, more experienced, and already 30km in.
Frustration is the enemy of all endurance athletes. More than that, though, it's the enemy of safety. When faced with an average speed far below your capability, with participants who give as much weight to the phrase "ride right pass left" as they do to "only take three ketchup packets" at New York Fries, judgment calls and decisions start to come in to play. Do I be risky to pass? Do I be slow to stay safe? What is the right call when?
The seemingly easy decision is to say "oh I'll just power by this group [on the right, up the middle, weaving through cones]", but in doing so you are unpredictable, and unpredictable actions create unpredictable results. Combine that with the promise of a dedicated cycling lane that really wasn't all that dedicated and narrowed suddenly and often, together with group riders that preferred to have the chats over following along single file minding their surroundings, and the results were too-often one or more individuals hitting the ground, hard.
And boy where there a lot of those. Some very very serious collisions with riders ending up with a face full of pavement and $3000 in repairs to equipment, if lucky. The stream of ambulances during the ride suggested that some were perhaps not so lucky.