It’s possible that crashes are as common as they’ve always been, but that broken bones are more common today than they used to be, making the crashes more serious and more frequently race-ending. As such, I think one potential culprit is osteopenia.
If you haven’t heard of it, consider it osteoporosis lite: bone mineral density is lower than normal. I think it should be considered a factor in all crashes where bone breakage occurs, whether it is in training or racing. Anecdotally, there seem to be more and more stories about guys breaking bones in training crashes the past several years. Even “normal” cyclists can have reduced bone density as a result of all the miles they put in, so a Tour rider, particularly a climber who has meticulously starved himself down to his ideal race weight, probably has thinned his bones beyond what the average mileage-hound has done.
I heard physiologist Allen Lim discussing hearing about crashes and thinking that every crash has the potential to break bones during a Grand Tour. When I put it to Dr. Michael Ross, a former team doctor, he unhesitatingly said, “yes.” It also could be a sign of cortico-steroid abuse, something Dr. Ross pointed out, as the result is same. Yes, these guys are racing hard, yes, they’re going fast, yes, they’re hitting the ground hard, but looking at how emaciated riders like Brad Wiggins and Chris Horner are at their Tour weight, I have to imagine their bodies catabolized bone matter to keep going.
It strikes me as an evolutionary strategy that certainly helped early humans survive famines, but it also could be how crashes are breaking collarbones, ribs, pelvises, wrists, hips, and so on. For all the discussion about injuries resulting from race crashes, lots of guys seem to be breaking bones training; Dutch rider Robert Gesink had his season ended for him shortly before the World Championships when he fractured his leg while out training.