[1][2] A few days before the Tour started, it became known that Paul Gutty had failed a doping test when he won the French national road championship.

The teams entering the race were:[1] After his dominating victory in the previous year, Merckx was the major favourite.

[5] Merckx had already won important races in 1970, including Paris–Roubaix, Paris–Nice, the Giro d'Italia and the Belgian national road championship.

[6] Luis Ocaña, who had won the Critérium du Dauphiné Libéré and the Vuelta a España, suffered from bronchitis, but still started the Tour, unable to seriously challenge Merckx.

[6] The highest point of elevation in the race was 2,115 m (6,939 ft) at the summit of the Col du Tourmalet mountain pass on stage 19.

[8][9] The big favourite Merckx won the opening prologue, but he decided not to try to keep this leading position during the entire race.

Merckx' teammate Zilioli was ranked highest amongst the escaped cyclists, and none of them were considered competitors for the general classification, so Guillaume Driessens, Merckx's team leader, allowed the breakaway to work, and told Zilioli and Vandenberghe to give their best.

[16] Stage 3B was won by Marino Basso who edged Walter Godefroot and Cyrille Guimard in the sprint.

Guimard took the green jersey from Jan Janssen as Zilioli kept his narrow lead in the overall situation.

He was caught right at the finish line and passed at the last possible second by De Vlaeminck and Godefroot, who took the stage win.

Duyndam did all of the work and the two of them survived to the finish about ten seconds ahead of the hard charging peloton.

[19] Merckx was now in the maillot jaune with Godefroot in 2nd by a few seconds and De Vlaeminck, Janssen and Van Springel less than a minute behind.

He finished ten seconds ahead of Lucien Van Impe, but won considerable time on those closest to him in the GC.

José Antonio González Linares put in the fastest time with Merckx three seconds slower.

In the sprint, Agostinho expected his teammate to give him the victory because he had done all the work, but to his surprise Frey started to come around him.

The race jury did not allow this, and gave the victory to Frey, putting Agostinho in second place.

The rest of the field was considerably distanced with Gösta Pettersson rising from outside the top 10 all the way up to 4th place at +7:44 because he finished within a group including Francisco Galdós and Johny Schleck who themselves put several minutes of time into the other contenders.

Zoetemelk said that he would focus on defending his second place, because he thought Merckx was better than the rest of the world.

11B ended in a sprint with Basso taking his second stage win ahead of Godefroot and Janssen, all of whom were competing with Merckx in the Points Competition.

Zoetemelk was on the podium in 2nd, Gösta Pettersson in 3rd and Salvarani won the team classification, based on their rider's performance during the final time trial ahead of Kas–Kaskol.

The next year there was an award for the youngest rider to finish the Tour, a color television which was won by Zoetemelk.

Merckx was the third cyclist to win the Giro-Tour double in one year; Fausto Coppi and Jacques Anquetil had done it before.

[30] The margin with the second placed cyclist was less than the year before; according to J.B. Wadley, the difference was that Merckx stopped attacking in 1970 after the Mont Ventoux; had he been inclined to win more time, he probably would have been able to.