I almost hesitate to share this story because I feel pretty dumb. But if it helps someone else avoid a problem, it will be worth sharing a story that highlights a bad call on my part. I always seem to have to learn lessons in expensive and painful ways, and the trend continues.
Yesterday on a group ride, I crashed hard. Nothing broken on me (that I know of) or the bike, but I have a lot of soreness and pain to deal with. It broke my helmet and I have some pretty good sized goose eggs and abrasions, etc. Shoulder and hip are pretty painful too. I'll probably go see the doc tomorrow just to make sure I don't need further attention.
The cause of the crash was entirely my fault. I was closing on the rider in front of me and violated his wheelspace. I hooked a wheel when that rider suddenly moved over, not knowing I was there and down I went, fortunately on the grassy side of the road.
In retrospect, I should have just drug a brake to kill the closure speed and stay out of his wheelspace. But as I've done many times before (with no issues), I just eased up and moved off to one side of the rider I was closing on, just getting my front wheel inside his wheelspace while my speed bled off so I could maintain my spot in the paceline.
If you're going to get in somebody's wheelspace, make sure they know you are there. Either pass them or stay behind them, but don't get in that blind spot and expect to emerge unscathed.
Lesson learned... the hard way, of course.