I don't think it is a coincidence. People in their 50s were youngsters during the last big cycling boom in the U.S. (late '60s to early '80s). Many of us took it up as a lifestyle; we've been quite lonely out there until recently. I think we are still riding a disproportionately large segment of the miles ridden. Add in the fact that we are often caught still assuming we live in a somewhat civilized nation where people pay attention while driving (bad assumption these days) and our slowed reflexes and failing vision and we are ripe for the canary role.