About two and a half years ago. I was riding a mountain bike trail that I'd been on twice before. I felt really good and kept thinking, "Faster! Faster!"
Which was all good until the abrupt stop. I lost control of the bike, went over the handle bars. I'm guessing I was doing about 30 miles an hour. Got road rash in my arm pits. That was a treat. Then, discovered that I tore a rotator cuff. This in turn caused my bursae to inflame. Over the next year, I struggled with the injury/inflammation and then I managed to sever a tendon in my shoulder. So... two surgeries later and I don't ride so much any more.