Chris Froome (Team Sky) managed to fend off attacks from his overall Tour de France rivals on the first full day in the Alps, which saw American contender Tejay van Garderen (BMC Racing) withdraw from the race and Alberto Contador (Tinkoff-Saxo) lose time due to a crash.
Despite challenges from Nairo Quintana (Movistar), Vincenzo Nibali (Astana) and Contador, Froome safely retained the race lead ahead of Quintana, who remains three minutes and 10 seconds down. Valverde is now third at 4-09, with Geraint Thomas (Team Sky) fourth at 6-34.
Van Garderen was forced to abandon the race after suffering with illness during the stage. The American contender was third overall at the beginning of the day. After being dropped early on in the stage, then catching back up to the peloton, he was then dropped again and decided to call it a day, visibly upset as he was picked up by a BMC team car.
It was another day with two races: one for the overall riders and one for the stage honours. German Simon Geschke (Giant-Alpecin) took the stage win have attacked from the day's large escape group. He won solo ahead of Andrew Talansky (Cannondale-Garmin) with Rigoberto Uran (Etixx-QuickStep) in third.
The Great (Big) Escape
After some initial unsuccessful attacks at the start of the day, a 28-rider lead group formed including Sky's Richie Porte and Nicolas Roche, Mathias Frank (IAM Cycling), Peter Sagan (Tinkoff-Saxo), Andrew Talansky (Cannondale-Garmin), Thibaut Pinot (FDJ), Adam Yates (Orica-GreenEdge), Steven Kruijswijk (LottoNL-Jumbo) and John Degenkolb (Giant-Alpecin).
Contador attacked with team-mate Michael Rogers half-way up the second category Col de la Colle-Saint-Michel. Although he was swiftly caught, his acceleration had the effect of blowing the peloton to pieces, leaving a select group of favourites with over 70km still to go.
A slowing of the pace on the run-up to Col d'Allos saw a number of riders rejoin the group containing Froome, Quintana, Nibali and Contador. Sky once again took up position at the front to set the pace.
Geschke attacked off the front of the break as the road started to climb towards the Col d'Allos. He continued to forge ahead alone, growing his advantage. With 30km to go he was two minutes ahead of the break and 10 minutes in front of the bunch.
Yates, Talansky, Pinot, Frank and Kruijswijk moved ahead of the remnants of the break to chase Geschke. Then Pinot attacked them to try his luck in chasing Geschke himself.
Geschke crested the summit of Col d'Allos solo and onto the technical descent with Pinot a minute behind. Pinot crashed on a corner, slowing his pursuit and allowing Talansky and then Uran to catch and pass him. Geschke ultimately evaded the chase from Talansky, taking a fifth stage win for Germany. British Tour debutant Adam Yates finished in 10th place.
Behind the stage winner, first Nibali and then Quintana attacked the yellow jersey group. Froome marked both accelerations as Porte joined them after waiting from the earlier escape. Contador crashed on the descent, lost time in trying to sort out his bike and was temporarily forced to use Sagan's bike. But by then, the Froome group were long gone.
Froome kept pace with Nibali on the descent, with Valverde and Quintana in close proximity, and the quartet hit the final climb together. Movistar's numbers were swelled to four by two riders joining them from the break. Contador was without team-mates two minutes behind, chasing hard to try and reduce his time deficit.
Quintana tried to attack several times in the final kilometre, with Froome following his moves. The pair managed to gap Nibali and Valverde in the final 500 metres. Thomas came over the line a minute after team-mate Froome but over a minute ahead of Contador to move up to fourth overall as Contador slipped to fifth, 6-40 behind Froome.
Bennett and Kwiatkowski out
Irish sprinter Sam Bennett (Bora-Argon 18) and world champion Michal Kwiatkowski (Etixx-QuickStep) were among the day's abandons. Bennett had started the day as last-placed rider in the general classification, and told Cycling Weekly yesterday that he was finding it tough but hadn't expected to make it to the Alps.
The climbing continues on Thursday on stage 18, a 186.5km trip from Gap to Saint-Jean-de-Maurienne that boasts seven categorised climbs, including the hors catégorie Col du Glandon that peaks at 40km from the finish.
>>> Tour de France 2015 stage 18 full preview
Tour de France 2015, stage 17: Digne-les-Bains to Pra Loup, 161km
1. Simon Geschke (Ger) Giant-Alpecin in 4-12-17
2. Andrew Talansky (USA) Cannondale-Garmin at 32 secs
3. Rigoberto Uran (Col) Etixx-QuickStep at 1-01
4. Thibaut Pinot (Fra) FDJ at 1-36
5. Mathias Frank (Swi) IAM Cycling at 1-40
6. Steven Kruijswijk (Ned) LottoNL-Jumbo at 2-27
7. Nicolas Roche (Irl) Team Sky at 3-02
8. Jonathan Castroviejo (Spa) Movistar at 3-04
9. Serge Pauwels (Bel) MTN-Qhubeka at 3-05
10. Adam Yates (GBr) Orica-GreenEdge at 3-21
18. Nairo Quintana (Col) Movistar at 7-16
20. Chris Froome (GBr) Team Sky at 7-16
21. Alejandro Valverde (Spa) Movistar at 7-23
22. Vincenzo Nibali (Ita) Astana at 7-31
24. Geraint Thomas (GBr) Team Sky at 8-18
31. Alberto Contador (Spa) Tinkoff-Saxo at 9-33
DNF Tejay van Garderen (USA) BMC Racing
Overall classification after stage 17
1. Chris Froome (GBr) Team Sky at 69-06-49
2. Nairo Quintana (Col) Movistar at 3-10
3. Alejandro Valverde (Spa) Movistar at 4-09
4. Geraint Thomas (GBr) Team Sky at 6-34
5. Alberto Contador (Spa) Tinkoff-Saxo at 6-40
6. Robert Gesink (Ned) LottoNL-Jumbo at 7-39
7. Vincenzo Nibali (Ita) Astana at 8-04
8. Mathias Frank (Swi) IAM Cycling at 8-47
9. Bauke Mollema (Ned) Trek Factory Racing at 11-47
10. Warren Barguil (Fra) Giant-Alpecin at 13-08
37. Adam Yates (GBr) Orica-GreenEdge
Video: Tour de France 2015 in the Alps
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