Tough health rules mean that the event may have to be halted long before it arrives on the Champs Elysee in Paris at the end of the Grand Finale, currently due in three weeks' time.
Socially-distanced spectators turned up to see "Le Grand Depart" in a much more muted atmosphere than normal.
The French cycling event was delayed following President Emmanuel Macron's announcement that events with large crowds could not take place until at least mid-July.
Bernal rode into the central square of Zipaquira on his bike wearing the Tour's famed yellow jersey
After Saturday's 20th stage, Bernal is set to win the Tour de France 2019, despite mudslides hindering they cyclists' path.
A hailstorm in the Alps stopped Friday's stage of the Tour de France after it left the road impassable, organisers said.
The 106th edition of the legendary cycling race kicks off in the Belgian capital on Saturday. The 176 riders will battle it out over 3,400 kms for the coveted yellow jersey.
Four-time Tour de France winner Christopher Froome is out of this year’s race after a serious accident while training, his manager has confirmed to French television.
"I’m not sure whether this is a bike shop, an art gallery or a museum"
Welshman negotiates final time trial
Geraint Thomas was in prime position to win his maiden Tour de France after he retained the overall leader's yellow jersey in a lively 19th stage won by Slovenian Primoz Roglic as defending champion Chris Froome slipped down to fourth on Friday.
Julian Alaphilippe's descending skills made the difference as the Frenchman claimed his second victory in this year's Tour de France to take the 16th stage.
Tear gas fired by police forces riders to stop