Not against other contenders for the podium. They are long gone in the British rider's rear-view mirror. But against skeptics created by the cheating of Lance Armstrong and other dopers, and against the legions of fans they betrayed.
For many of those cycling fans, Froome's performances are so good that they must be too good to be true. The leader of Team Sky said one spectator even hurled a cup of urine at him this weekend, shouting "Doper!"
In short, Froome finds himself in the impossible position of being damned by his own success. No matter how many times he insists that he is clean, the words fall on deaf ears. As they would: After all, Armstrong used to say that, too.
Froome understands that. He knows that the yellow jersey he wears has been so soiled by the deceit of those who wore it before him that some of that dirt, deservedly or not, is going to rub off on him, too.
Being doubted, being hauled over of the coals of suspicion day-in, day-out, is the bill that must be paid now for winning a post-Armstrong Tour, especially when you're crushing rivals with apparent ease like the American did on the seven Tour victories that were later stripped from him.
Two weeks in, the skepticism is getting under Froome's very thick skin. It's hard to find a more mild-mannered chap in the peloton than the gangly, sometimes awkward, Kenya-born Briton. But as he prepares for the Alps, the ultimate test at this Tour, a hardening in his attitude and tone is unmistakable.
He blames "very irresponsible" media for turning public opinion against him. He started on that theme Saturday after the urine incident and developed it Sunday after safely negotiating Stage 15 that ended with a bunch sprint won by Andre Greipel. It was the German's third victory at this Tour, and it left Froome's large lead intact.
"If people are led to believe that these performances are not legitimate, that's what's going to push them to start booing, and to start punching and spitting and throwing urine on riders," Froome said.
And for those who will still listen, he again repeated that "times have changed" from the Armstrong era.
"This isn't the wild west that it was 10 or 15 years ago," he said. "Of course, there are still going to be riders who take risks in this day and age, but they are the minority.
"It was the other way around 10 or 15 years ago. There is no reason in this day and age for that level of suspicion to continue. There's absolutely no reason."
Still, French police took no chances. Following the urine assault, they posted half a dozen officers around Team Sky's bus at the start of Sunday's 183-kilometre (114-mile) stage from Mende to Valence.
Because of its flat finish, Stage 15 represented the last opportunity for heavy, muscular sprinters to shine before light but strong climbers like Froome take back the spotlight in the Alps in the last week, after a rest day on Tuesday.
It meant that sprinters' teams wouldn't let a breakaway group of riders steal the stage victory from under their noses.
The pack rode so furiously that Mark Cavendish, the only rider to beat Greipel in a massed bunch sprint at this Tour, wasn't able to compete for the win in Valence because he was dropped early in the hilly stage that flattened out at the end. Cavendish said stomach problems kept him up the previous night, leaving him feeling empty.
Telling himself "you have to hang on here," Greipel managed to stay with the pace. He credited his Lotto-Soudal teammates for positioning him "in the right spot" for the final sprint. From there, he did the rest, choosing just the right time to accelerate away in the last 300 metres (yards).
"I had the power in my legs to finish it," he said. "It's all about the legs. Mother Nature gave me this."
John Degenkolb of the Giant-Alpecin team was second, Katusha's Alexander Kristoff third. Greipel also won stages 2 and 5.
Monday's Stage 16 takes the Tour into the Alps' foothills to Gap. With two moderate climbs followed by a downhill finish, it should suit punchy riders lower down in the overall standings who are looking for a win before the podium challengers do battle in the really big mountains.
Out on the road at least, everything is going to plan for Froome. He finished safely in the main pack with the other podium favourites, and there were no changes in their overall placings.
Froome still leads second-placed Nairo Quintana by 3 minutes and 10 seconds. Tejay van Garderen of the BMC team remains 3:32 back in third.
Jamey Keaten in Valence contributed to this report.Suggest a correction