The two stages in the heart of the Brittany hills represent a high-speed, back-to-back test of nerves and fitness for the overall contenders at this year's Tour de France, with everyone scared and determined not to lose time to their rivals so early in the race.
Stage 5 to Quimper ended with a sprint finish and a select group of 38 riders finishing on the same time. Thursday's sixth stage is much harder, with two times up the Mur de Bretagne climb and a finish atop the two-kilometre climb that kicks up in double digits and then eases near the finish. Any tiny gaps that open between the wheels can rapidly become significant and precious time differences.
All the overall contenders were relieved to finish together in Quimper but know that the Mur de Bretagne has always produced time gaps - in 2011 when Cadel Evans beat Alberto Contador in a photo finish, and again in 2015 when Vincenzo Nibali lost 10 seconds.
In Quimper Bob Jungels (Quick-Step Floors) was last in the front group in 38th place. If he or anyone else had been on the wrong side of even a one-second gap to the rider in front, their time gap would have been measured against the moment when Sagan hit the line, so they would have lost at least 14 seconds. Such are the rules on timing in Grand Tours and stage races.
Fortunately, every overall contender made sure they were up tight and close to the riders in front in the group that followed Sagan over the line.
Michal Kwiatkowski (Team Sky) could have perhaps challenged for the stage win, but he sacrificed his own chances to work for Chris Froome and Geraint Thomas. They were happy to avoid losing time.
"It's the kind of stage where something could definitely go wrong, and quite quickly you could find yourself losing 30-40 seconds if you're caught out of position, so it was just a day to stay up front and really stay on it," Froome explained post-stage. "I'm happy, the guys rode fantastic, took the race on in the last 20-30 kilometres and kept us up front really well, so I'm very happy with that."
Thomas compared the stage to a Spring Classic.
"It was tricky at times – a bit like a Classic," the Welshman said. "It was a stressful day fighting for position from the start on a lot of narrow roads, up and down and quite a lot of climbing in the end so it was a tough day. We wanted to be at the front with six kilometres to go onto the narrow section before the final descent, and we nailed that and kept right out of trouble. The boys rode really well together, so all good."
Richie Porte (BMC Racing) stopped just through the finish area, keen to douse his head with cold water and mentally switch off after an intense five hours in the saddle.
"It's just nice to get it done and not lose time," Porte told Cyclingnews. "We came to ride the Tour de Finistere in April to look at the roads and it was a good call. It was a hot, hard stage and so it was good to tick it off. Today we raced it super fast. This was the hardest stage by far."
Tom Dumoulin was also happy not to lose time but was disappointed that teammate Michael Matthews was not there to try to win the stage for Team Sunweb.
"Looking at the results, Michael would have been in the mix for the win, but that wasn't meant to be," Dumoulin said. "We will miss him for the stage results and for helping me. I feel good, my legs are OK but not yet super," Dumoulin said, perhaps playing bluff with his rivals and himself.
Every second counts in the virtual GC
Despite the early crashes and the team time trial, the overall classification remains tight.
Nairo Quintana (Movistar) is worst off, some 2:10 down on leader Greg van Avermaet (BMC Racing) and 2:05 down on Geraint Thomas in the virtual GC classification. Everyone else is spread over 120 seconds, with Dumoulin only eight seconds down on Thomas, while Rigoberto Uran (EF Education First-Drapac) is at 32 seconds, Porte at 48 seconds and Froome at 52. Adam Yates (Mitchelton-Scott) is at exactly 1:00, Vincenzo Nibali (Bahrain-Merida) is at 1:03 and Romain Bardet (AG2R La Mondiale) is at 1:12.
That virtual GC will likely be shuffled again atop the Mûr de Bretagne as the Tour de France continues to balance on a knife-edge of seconds during the stages in northern France. Positioning will be vital yet again to avoid being on the wrong side of a late split.
"I felt good and so hopefully we can do something. For sure you don't want to have a bad day on the Mûr de Bretagne, " Porte said, seemingly inspired by Van Avermaet being in the yellow jersey.
Froome was also wary of the climb.
"Tomorrow will be interesting, the Mûr de Bretagne two times, you always see a bit of action there. I'm looking forward to it actually, I much prefer those stages to the fast flat days so it will be fun again."
GC contenders after stage 5
|2||Tejay van Garderen (USA) BMC Racing Team||18:22:02|
|4||Geraint Thomas (GBr) Team Sky||0:00:03|
|6||Bob Jungels (Lux) Quick-Step Floors||0:00:07|
|7||Tom Dumoulin (Ned) Team Sunweb||0:00:11|
|9||Rigoberto Uran (Col) EF Education First-Drapac p/b Cannondale||0:00:35|
|10||Rafal Majka (Pol) Bora-Hansgrohe||0:00:50|
|11||Jakob Fuglsang (Den) Astana Pro Team||0:00:51|
|12||Richie Porte (Aus) BMC Racing Team|
|13||Alejandro Valverde (Spa) Movistar Team||0:00:53|
|14||Mikel Landa (Spa) Movistar Team|
|15||Chris Froome (GBr) Team Sky||0:00:55|
|16||Adam Yates (GBr) Mitchelton-Scott||0:01:00|
|17||Vincenzo Nibali (Ita) Bahrain-Merida||0:01:06|
|18||Romain Bardet (Fra) AG2R La Mondiale||0:01:15|
|19||Primoz Roglic (Slo) LottoNL-Jumbo|
|20||Steven Kruijswijk (Ned) LottoNL-Jumbo|
|22||Bauke Mollema (Ned) Trek-Segafredo||0:01:16|
|24||Daniel Martin (Irl) UAE Team Emirates||0:01:38|
|29||Ilnur Zakarin (Rus) Katusha-Alpecin||0:01:51|
|33||Nairo Quintana (Col) Movistar Team||0:02:08|