Tour director Christian Prudhomme condemned the farmers' action and demanded more respect for riders. Two key crashes on risky descents.
Farmers rolled large hay bales into the road 29 kilometres into Tuesday's stage from Carcassonne to Bagneres-de-Luchon.
The overall standings were unchanged.
"Nothing stuck, however, as the GC men safely negotiated the descent to finish together - ensuring another day in the yellow jersey for Geraint Thomas, who remains 1'39" ahead of team-mate Chris Froome.
Dressed in his race kit but covered with a grey jacket, Froome (Team Sky) was accosted on his descent back down the final climb to his team accommodation. "They won't attack from the starting line", Steels says, adding that the only instance where an immediate attack could occur is if one team has four or five riders in the top 20.
"It's just one of those things".
"We feel safe. Obviously on some of the climbs not everyone's our fans but we don't feel threatened", Thomas said. It's really appreciated that you get support in these hard moments. It's not like football or something. Froome upset the race, riding away to the race lead in stage 19, snatching the pink jersey from Simon Yates (Mitchelton-Scott).
Stephane Mahe Reuters
The small group of farmers from the Aude department were protesting a planned reduction of European Union funding, according to French authorities. "People should not block the road, no matter what causes they are fighting for".
"It was a tough day, an intense day, but I've got no regrets", Froome said. "But if it's 110 kilometers, anything can happen, even for the GC contenders", says Franco Pellizotti, the Italian who at 40 is the oldest rider in this Tour. I went all out for 220 kilometers today.
Belgium's Philippe Gilbert attempted to break clear as the stage progressed but the Quick-Step Floors rider's effort ended in dramatic circumstances when he crashed when descending the Portet d'Aspet.
"I don't know how you prepare", Thomas says. "It just gave me confidence, that someone of his stature was struggling".
"It's pure happiness after a day of suffering", said Alaphilippe, who tightened his grip on the polka dot jersey for the mountains classification. My morale is pretty damaged right now.
Yates was quickly back on his bike, and followed home Bahrain-Merida's Gorka Izagirre to finish third.
Quintana's victory is the third for Colombia at this year's Tour de France; sprinter Fernando Gaviria won two stages in the first week of racing.
"This stage is going to be massively decisive, there are going to be big gaps", said Thomas.
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