The peloton may once have been described as the "convicts of the road", but they share an innate sense of sportsmanship and fair play.
Armstrong went on to win stage 15 after crashing
Lance Armstrong's victory on stage 15 was due partly to a sporting gesture from the elite group of riders surrounding the yellow jersey on the final climb to Luz-Ardiden in the Pyrenees.
Armstrong fell after colliding with a spectator, but instead of seizing their opportunity, the group, which included his closest rival Jan Ullrich, sat up and waited for Armstrong to remount.
Once they were back up to racing pace, Armstrong surged forward to win by 40 seconds and opened up a crucial 67-second gap over 1997 champion Ullrich with five stages left.
Such sporting gestures are a long-held tradition in the professional peloton, which ironically has been plagued by accusations of cheating through the use of performance-enhancing drugs.
"The Tour de France is special but it's normal practice for this type of thing to happen," former British Tour rider and Team CSC number two Sean Yates told this website.
"You are racing against the same guys day-in, day-out and it's in everyone's best interest to get along the best they can."
In the 2001 Tour, Armstrong and Ullrich were locked in an epic high-speed tussle as they plummeted down the descent of the mighty Col de Peyresourde in the Pyrenees.
But the German misjudged a corner and plunged off the road.
Instead of making good his escape, Armstrong waited to see if his rival was fit to continue and then coasted while the shaken Ullrich picked himself up.
And Yates insisted that what goes around, comes around in cycling.
"They were paying back that gesture," he said of Monday's act of sportsmanship.
"If everyone behaves in the same way it all evens itself out in the end. And it's best for the sport."
The unwritten rule extends to any misfortune, or even call of nature, that befalls the yellow jersey or a prominent rider in a breakaway.
"There are times when a lot of people stop [for a call of nature] and especially if it's the yellow jersey, the unwritten rule is you don't attack at that point," said Yates.
But he warned that the gentleman's agreement must not be taken for granted.
"If there's a crash and it's out of people's control and the whole bunch are storming along not everyone will sit up," he said.
"But in yesterday's case it was a small, elite group of riders and everyone knew what happened and it was best that they behaved that way.
"It would have been the same if there had been a puncture.
"But sometimes mistakes are made. You have to be careful and can't assume that everyone will stop."
If the agreement is broken, the miscreant can expect a severe tongue-lashing from the other riders.
And they may seek retribution further down the line by preventing him from winning a stage or a one-day race.
As Yates said: "Lance won't forget."
But he insisted the days of the Tour's enforcers have gone.
"There's not many patrons like [Eddie] Merckx or [Bernard] Hinault left in the peloton," he said.
"Everyone was scared of them. No-one wanted to be on the end of Hinault's tongue. But those days are over."