Simon Geschke wins stage 17 at Pra Loup, Chris Froome in control

Giant-Alpecin's bearded all-rounder Geschke attacked from a breakaway of 25 riders with 53 kilometres remaining of the 161km stage from Digne-les-Bains. The 29-year-old tamed the long first-category climb of the Col d'Allos and its infamous descent before holding off a resurgent Andrew Talansky (Cannondale-Garmin) on the final climb.

American Talansky crossed the line 32 seconds down on Geschke to give his team its third bridesmaid's berth of the 102nd edition of the Tour. Colombian Rigoberto Uran (Etixx-QuickStep) took third place 1:01 in arrears while Frenchman Thibaut Pinot (FDJ) had to settle for fourth place after crashing on one of the many tight hairpin bends on the dangerous descent of the Col d'Allos.

Another sweltering day in the Alps claimed a huge casualty with the withdrawal of Tejay Van Garderen (BMC) half way through the stage. The American, who was in third place on the overall standings after impressing since the start in Utrecht, was reportedly suffering a respiratory infection.

There was further drama in the battle for the podium after Spaniard Alberto Contador (Tinkoff-Saxo) crashed on the descent of the Col d'Allos and was forced to swap bikes with team-mate Peter Sagan for the final 15km of the stage. The Giro d’Italia winner would lose more than two minutes to his rivals on GC.

Britain's Froome withstood numerous attacks from defending champion Vincenzo Nibali (Astana) and Movistar pair Nairo Quintana and Alejandro Valverde over the day’s five climbs.

Froome retained his 3:10 lead over Colombian climber Quintana after the pair finished side by side 7:16 down on stage winner Geschke.

As for Geschke, it was the finest hour for the man usually associated with doing domestique duties for his Giant-Alpecin team-mates Marcel Kittel and John Degenkolb.

“I think I’m going to need a couple of years to realise what’s happened to me,” said Geschke, who finished fourth in Monday’s stage to Gap. "I’ve been struggling with the heat so I thought I’d try and get in the break today and hope for the best. I’m so emotional to get this win.

“I knew I needed a gap before the final climb and so I went early. I didn’t want a repeat of what happened at Gap. I definitely rode beyond my limit of pain – but I’m very happy.”

Poised in third place coming out of the second rest day, Tejay Van Garderen was quickly distanced by the peloton on the opening climb, the Cat.3 Col des Leques, after a fast start to the stage.

Nursed by two BMC team-mates, the American fought his way back to the pack after the pace slowed on the Cat.3 Col de Toutes Aures, but soon called it a day when the tempo increased on the Cat.2 Col de la Colle-Saint-Michel 72km from the finish.

BMC later confirmed that the stricken 26-year-old had been suffering with a chronic migraine. In floods of tears Van Garderen clambered into his team car; it was the first time in his career that he has abandoned a Grand Tour

One rider certainly not ill or suffering from any lingering after effects of the rest day was the indefatigable green jersey. For the fourth consecutive stage, Peter Sagan found himself in the day’s main break after a series of attacks over the opening three climbs.

The 25-year-old all-rounder was denied maximum points at the intermediate sprint at Beauvezer after bizarre scenes saw Frenchman Benoit Vaugrenard (FDJ) steal up behind Sagan and John Degenkolb and cross the line in pole position.

Some choice words followed from the Slovakian – although an extra 15 points for third place saw him move more than 100 points ahead of nearest rival Andre Greipel (Lotto-Soudal) in the battle for green.

Before he stage Thibaut Pinot told L’Equipe that the descent of the Col d’Allos was one of the most dangerous in France – and it lived up to its billing when Pinot kissed the tarmac shortly after crossing the summit of the fourth climb of the day 1:10 behind lone leader Geschke.

Eager to make up time, Pinot had pedalled out of a tight left-hand bend, clipped the road with his left pedal and was sent sprawling across the road. He swiftly got back on his bike but, his confidence drained, the Frenchman was passed by Andrew Talansky, Rigoberto Uran, Mathias Frank (IAM) and Adam Yates (Orica-GreenEdge) before the descent was complete.

Eight minutes later, Contador crashed from a group of the main favourites in an incident unseen by the TV cameras. The Spaniard received help from team-mates Sagan and Mick Rogers – both of whom had featured in the break – but despite a bike swap with the green jersey, Contador was unable to return to the yellow jersey group.

With Marcel Kittel ruled out of this year’s Tour, Giant-Alpecin looked to John Degenkolb for stage wins. Those never came – but Simon Geschke has managed to save his team’s Tour after a gutsy solo break from more than 50km out.

Geschke delivered Germany its fifth win of the race following Andre Greipel’s hat-trick and Tony Martin’s win over the cobbles. He also restored the peloton’s faith in beards after the setback dealt to facial hair following the expulsion of Luca Paolini, the Italian veteran who tested positive for cocaine in the opening week.

Special mention also to Swiss Mathias Frank: his fifth place saw the IAM rider zip up into the top ten.

Tejay Van Garderen was the most high profile of six withdrawals in stage 17 – closely followed by world champion Michal Kwiatkowski of Etixx-QuickStep. But most aggrieved of riders left in the race will be Alberto Contador, whose day started promisingly when he and team-mate Mick Rogers attacked on third climb, but ended under a cloud after that downhill crash.

Contador crossed the line on his own, 2:17 down on both Froome and Quintana, scuppering his already remote chances of securing a memorable Giro-Tour double. The Spaniard stays in fifth place following the withdrawal of Van Garderen, but now trails fourth-place Geraint Thomas by over a minute and the race summit by a huge 6:40.

A second day in the Alps sees the race tackle seven climbs en route to a downhill finish in Saint-Jean-de-Maurienne. The 186.5km stage 18 from Gap peaks out at the HC Col de Glandon 40km from the finish before throwing the 18 eye-catching hairpins – or ‘lacets’ – of Montvernier at the riders ahead of the finish.

There wasn't a dry eye in the house at the media zone after a rare win for one of cycling's outsiders...