Team Sky have become accustomed to a hostile reception in France as their domination of the race has grown since Bradley Wiggins's victory in 2012, as a combination of weariness with their success and suspicion over their practices have whipped up animosity among spectators.
It was not immediately clear whether protesters or police used the chemicals. After fans threw flares at riders in the climb to the ski resort of Alpe d'Huez, Tour organizers banned the use of smoke flares for the rest of the race.
Sky has uncommon wealth, vast ambition and an ability to stock its roster with riders with the talent to lead any squad in the peloton--all of which has created an unexpected headache.
Each of these riders are recognised as five-time Tour champions... and that's a claim that Froome started the 2018 Tour striving to equal. The man in front of him in the yellow jersey.
"I don't know how you prepare", Thomas says. "It's the last mountain top finish that will prove most decisive", said Thomas.
But for Thomas, his relationship with Froome goes beyond the race and the team. We've still got a strong team.
"I was not affected because I was not in the first 10 of the group", he said.
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Team Sky manager Dave Brailsford.
"We've seen the finals of all three, it's a tough old finish [on stage 16], then obviously the short stage, which is tough and Thursday sees a lot of climbing and the Tourmalet then down into the finish there".
Froome was initially barred from starting his title defence by organizers because of the suspicion surrounding his "adverse analytical finding" for the asthma drug salbutamol at the Tour of Spain past year.
"We're in this wonderful position and it's not up to us to be attacking", Froome said.
"This is happening just as we are trying to call the fans to be calm, to make sure that the riders - their riders - and especially Chris Froome, are respected".
Italian rider Gianni Moscon of Team Sky has been disqualified from this year's Tour de France, captured on camera attempting to punch Fortuneo-Samsic's Elie Gesbert in the opening moments of today's 15th stage.
"The Tour is promoted as the world's greatest annual global sporting event".