‘‘What’s scary is there is no conversation about it,’’ he says. ‘‘We don’t talk to each other about this. ... It’s a real problem for the future of our society.’’

Spectators like Driller, a 28-year-old sports physiologist, are also watching these changes with some disquiet.

‘‘I'd much rather have seen it than have a picture to post on Facebook,’’ he says. ‘‘If you’re crazy enough to come out in the rain, you want to see the event — even if you get a little wet.’’

Don’t tell that to Jane Markley, walking down the road near Hyde Park Corner busily scrolling through her images after the race. Had she missed the picture, would she feel as if she missed the event?

‘‘Absolutely,’’ says the 60-year-old from Washington, D.C. Then she found it — hurrah! — proudly showing off the fact that she did indeed get a few cyclists and some water spritzing up from the wet pavement.

There it was. Irrefutable proof: ‘‘I was there.’’

___