Geraint Thomas (Team Sky) became the first British Tour de France stage winner at Alpe d’Huez and in doing so also became the first rider to win a road stage to the ski resort wearing the yellow jersey. He outsprinted Tom DuMoulin (Team Sunweb), Romain Bardet (AG2R La Mondiale), Chris Froome (Team Sky) and Mikel Landa (Movistar Team) to extend his lead in the general classification.
161 riders started stage 12 at Bourg-Saint-Maurice with one non-starter: last year’s runner up Rigoberto Uran (Education First). After a fast start in the Tarentaise valley, Warren Barguil (Fortuneo-Samsic) was the first climber in action up to the Col de la Madeleine.
A front group of thirty riders was formed on the mountains and the group split several times. GC contenders Steven Kruijswijk (LottoNL-Jumbo), Ilnur Zakarin (Katusha-Alpecin) and Alejandro Valverde (Movistar) were part of it, as well as KOM contenders Julian Alaphilippe (Quick Step), Serge Pauwels (Dimension Data) and Barguil.
Alaphilippe and Gregor Mühlberger (Bora-Hansgrohe) rode away on the descent of Col de la Madeleine. They waited for their former breakaway companions and Pierre Rolland (Team EF Education First-Drapac p/b Cannondale) then escaped at the exit of the feed zone at Saint-Avre (km 74.5).
Rolland crested the Lacets de Montvernier alone in the lead and was joined at the bottom of the Col de la Croix-de-Fer by Valverde and Kruijswijk who was the virtual leader of the Tour de France as Team Sky led the bunch with a deficit of four minutes.
Barguil was first to rejoin them on the climb and it became an 11-man front group with 80 kilometres to go. Kruijswijk rode away solo 73 kilometres before the finish. He gained a maximum advantage of 6’15” over the peloton led by Mathias Frank for AG2R-La Mondiale and later by Marc Soler for Movistar but Team Sky seized the reins of the pack again on the descent to the Oisans valley.
Kruijswijk started climbing to Alpe d’Huez with an advantage of 4’20” over a group of thirty riders comprising all the members of the top 15 overall and it was down to 3’30” with 10km to go. Successively, Vincenzo Nibali (Bahrain-Merida) and Nairo Quintana (Movistar) tried to escape but Team Sky brought them back quickly.
The attack by Romain Bardet (AG2R-La Mondiale) with 7.5 kilometres to go enabled the Frenchman to ride away until he got caught with 4 kilometres to go by Froome who overtook Kruijswijk 3.5 kilometres before the line.
Bardet attacked again with 2.5 kilometres to go. While Nibali was chasing back after crashing, five riders were reunited at the front and Thomas proved to be the fastest of them all to take the stage and extend his overall lead.