There were three significant chain incidents that cost riders dearly in two events, the Men's and Women's elite. Katie Compton dropped her chain on the 1st lap and found herself way down. Now that ultimately did not change any standings as K.C. got into motor mode to secure a podium spot the last half of the race (and no one was going to touch Marianne Vos yesterday).
Then in the Men's elite, Jonathon Page dropped his chain and according to our forumite who was there, struggled to get it back on and dropped from 10th to 30th. And last, but most significant in terms of end results, Kevin Pauwels dropped his chain, struggled to get it back on and had to stop a 2nd time. Pauwels was riding very strong, pushing the lead group and riding like a given for the podium when that happened (and virtually guaranteeing an all Belgium podium).
So significant chain issues on both podiums plus host country's best man. Not a good day for the chain manufacturers (or indeed the systems those chains run on). By comparison, I heard only one incident of a puncture affecting the race; Moury of France who flatted after he was starting to blow anyways and then fell way out of contention. Tire reliability has always been an issue for bicycles and probably will continue to be for a long time. But chains shouldn't be. And especially chain issues that cost riders far more time than flats.
As an engineer, what I witnessed disappointed me. I was viewing systems performing poorly at the highest level of professional sports where money is no object. Watching a racer trying to yank out a jammed chain while dropping 10 or 20 places, well that is old footage from the 1930s, right? And he is probably riding on with a bent link and it might well happen again. (I'm betting that was Pauwels' issue. I've done that myself on the road.)
Every time I get on my 1/8th inch chain fix gears, I get reminded that I am riding the high point of the bicycle drive chain evolution for simple engineering elegance.