Cyclists had already passed when the blasts occurred
No-one was injured in the blasts, which officials said followed a phone call from the Basque separatist group Eta.
The small explosions occurred just outside the town of Belagua, 1km (half a mile) from the French border.
Eta has waged a violent campaign since the 1960s for an independent state in northern Spain and south-west France.
Officials said the devices, which included only "a small amount of explosives", were placed on either side of the road and hidden in plastic food containers.
They did not explode until some time after the cyclists had passed through the town, according to local media.
It is not the first time that Eta, which called off a ceasefire in June, has targeted the top cycling event to draw attention to its aim of achieving an independent Basque homeland.
Authorities in Spain say that at least two explosive devices were found on a section of the Tour de France bicycle race just outside the Spanish town of Belagua. Authorities say that "a small amount of explosives", were placed inside plastic food containers then placed on both sides of the road.

There are no reports of injuries but conflicting reports say that the cyclists passed the area before the devices went off, while others report that the devices were detonated before the cyclists passed.

The Basque separatist group known as the ETA have claimed responsibility for placing the devices on the route. A telephone call was placed to authorities by someone claiming to be from the ETA who threatened to use the devices.