The British national champion proudly showed off his red, white and blue colours on the 50th anniversary of Tommy Simpson's death on Mont Ventoux, giving his all in a solo attack on the Port de Bales after being part of the 12-rider break of the day. However, he was eventually closed down by Team Sky close to the summit of the Col de Peyresourde as they tried but ultimately failed to steamroll their overall rivals and protect Chris Froome's yellow jersey, which Fabio Aru (Astana) took at the finish.
Cummings is arguably the best breakaway specialist in the peloton when it comes to tough Tour stages. He has the ability, determination and intelligence to ride them perfectly, even when he feels he bites off more than he can chew, like stage 12. He had put a star next to the stage in his race manual and so stepped up and went on the attack.
"At the start I actually thought today was too hard for me to be honest, and it proved it was," Cummings said, explaining the dilemma and fear he feels of missing out on best chance at a stage win.
"In the Tour you can't be so selective. You might say, 'This is the day, this is the day', and you might miss the break. Today I got in the break and once you're there you commit to it. I think there was a chance to win at Port de Balès. It was a chance, so you go full for it until the moment you can't do it.
"It's not black and white, there's grey. There are some stages you can say, 'No I can't do that', but there are ones like today where it's a bit grey – maybe if I have a good day and the right combination you can do it. It was worth a try.
"Despite not winning, it was also nice to get out in front in the jersey, especially today with Tom Simpson and everything. I'm pretty proud of the effort, unfortunately there's not much I can do if they chase behind. I can't really control that."
Cummings won the Prix de la Combativite prize for his efforts. It was of little consolation but also signalled a personal victory after his return from injury.
Cummings spent three months away from racing after crashing at the Tour of Basque Country. He broke his collarbone, scapula and sternum and took to the virtual indoor trainer platform Zwift to hold onto his race fitness. He proved he deserved his place in the Dimension Data team for the Tour de France by winning both the road race and time trial at the British National Championships.
He spent much of the opening week and a half of the Tour de France at the back of the bunch – his personal strategy to avoid the crashes and stress of the early stages. So he was champing at the bit as the Pyrenees loomed and took a shot at a third stage victory after success in 2015 and 2016. Yet he insisted he does not feel under pressure to perform.
"The only pressure is to do my best. I don't feel pressure," he said. "People look at me more but if you use your head and you're smart and you're strong it doesn't really matter.
"So far the race has been way too hard for me or kind of too easy. That's been a bit frustrating, but it was like this in 2015 and then all of a sudden we went into the hilly stages and I was able to do something.
"It's frustrating because you want to race, but we all have certain characteristics and sometimes the stage doesn't suit you, so you've got to be smart and wait, not try to force something."
Cummings promised to rest up during Friday's short-but-intense mountain stage to Foix but is looking forward to the hilly stages later in the Tour.
"There's a whole load of days that are quite good for me now. I feel my Tour is just beginning."