Was it the crash or surgery that ultimately took his life? Fractured vertebrae isn't usually a "big" deal for cyclist because it's not enough impact to cause serious trauma (like a car wreck).

I know this won't change anyone's mind but riding in these large group rides just isn't that safe unless you know all the riders are very experienced (i.e. recovery for a racing team).

The fast group rides I participate never get larger than 7 people in a group even though hundreds of people are riding. If they do get too larger it gets broken up as usually the stronger riders will either ride off the front or fall off the back.

Most common reasons I see crashes in large (fast) group rides:

1. Rough road ahead or pot holes causes a rider or two to panic and rather than a hold a line swerves and takes someone out. Holding a line can also destroy your wheels but it's better than the alternative.

2. Riders giving everything they have to keep up are fatigued and don't have mental acuity to be riding 25mph just a few inches from others. Mistakes happen (i.e. touch wheels).

3. Aero bars. Enough said.

4. Inexperience as a whole group. If members of the group don't ride together often then signals can get mixed up.

My condolences to his family.