I've only ever had one crash and it didn't involve anyone else.
On 5 July 2008, I was riding along on the last day of a three-week tour of the Chili and Peru. I was on a guided tour with three Americans, two Belgians, myself and a buddy.
We had just come down from a high section of the Andes Mountains and were on a flat valley floor. The leader, Americans and Belgians were the fast riders and were often very far ahead of me and out of sight. My buddy also trailed well behind me and was often out of sight. We rode at our own pace, saw the sights and took pictures. The chase truck then followed. There was only one road so there was no chance of getting lost.
I wasn't riding fast when I entered what turned out to be a decreasing radius curve which was in fact a U-turn. Out in the boondocks there are no road signs. I didn't realize I was in trouble until it was too late. I leaned the bike hard and dragged the brakes, but I went off the road into a large drainage ditch. It was a hard landing, but I wasn't knocked out.
The ditch was well down off the road and when my buddy rode by he didn't see me. He was paying close attention to that dangerous curve. However, when he caught up to the lead group who just happened to take a rest not far away, they realized I was off the road somewhere. In the meantime, the chase truck found me, and then the other riders arrived.
I had dislocated my right shoulder and was in some pain. The lovely BMW I was riding was a wreck and loaded onto the truck.
The nearest town was about 20 miles away and had a small hospital. I was x-rayed and put in a heavy plaster upper body cast to isolate my arm across my chest. Once firmed by the cast the shoulder wasn't too painful.
For $100. US dollars, my buddy hired a local to take us back to the Inca city of Cusco where there was an international airport and hotels. The crash was on Saturday and Monday morning we were able to fly out to Lima, pick up another flight to New York and then another flight back to Canada. For three days we lived in airports and on planes.
Once home, I immediately went to the hospital and x-rayed again. The ball of the ball-and-socket shoulder joint was too badly damaged, so I had surgery and a steel prosthesis inserted.
Very soon after surgery I was put on a schedule of physiotherapy which lasted nearly six months over the fall and winter, so I really didn't lose any riding time.
I worked very hard at the physio because I wasn't going to allow myself to be infirmed for the rest of my life. It worked and I have about 95% range of motion which is the best that can be expected. Day-to-day, it's as if the crash had never happened and my life is completely normal.
The following April I mounted my trusty Bonneville and rode it as if nothing had ever happened. 15 years later it's still the same.
Oh yes, BTW, I was 70 years old at the time of the crash