I suppose bikers will go for routine checkups and respond to the doctor, "Jeez, I've been riding for ten years and nobody ever told me it was dangerous!"
The lessons are the same from every public health concern: risky sex, obesity epidemic, smoking. Badgering people is really fucking annoying for everybody involved - so annoying that they'll have worse healthcare outcomes in general - and basically nobody will make lifestyle changes because of it. The most you can do with non-structural solutions is get people to take prophylactics or wear a helmet.