To me, "competetively" is an important word in that phrase. As opposed to "never ride again"
I think of "never ride competetively" as some injury that makes a rider less able than the slowest
rider of the field. I imagine some injury that may cause joints to become inflamed with use, or
maybe a back problem that causes major difficulty in leaning over. The back problem could be
skeletal, muscular, of ligament damage. A head injury that damages the ability to balance could
be a factor.

Maybe a hip replacement. Have him in a bad wreck that begins a crack in the
socket joint. Dr's say take it easy, but he feels ok and wants to risk it to get the next win. A subsequent crash turns the joint connection to splinters. Follow up with
replacement surgery and rehab, etc..