[bdndndndbve]

TFA says most of the injured people were wearing pads and they went head-first over the handlebars. Reading between the lines, it sounds like they landed on their heads and the forces on their spine caused injury. Much like CTEs in football, you're going to have a hard time protecting yourself against inertia.

[bluGill]

The article has most were wearing a helmet, but less than 10% other pads. I'm not clear on what other pads are, but they seem to include things like knee protection which I wouldn't expect to help in this type of accident (but probably help is much more common falls).