Jumbo-Visma rider Kuss attacked on the final climb of the day, the Col de Beixalis, with a huge effort 19km from the finish, eventually cresting the climb alone and descending to victory ahead of Alejandro Valverde (Movistar).
Kuss has shared his data from the immense ride on Strava, revealing how deep he had to dig to keep Valverde away on the final climb.
The 26-year-old claimed the Strava KoM on Col de Beixalis, a 6km climb with a brutal average gradient of 8.1 per cent, setting the fastest time out of the 9,000 people who have ridden the segment.
Kuss hit the summit with a time of 18-55, around 40 seconds quicker than the previous fastest time of 19-36, set by Pavel Sivakov (Ineos Grenadiers) during a training ride in May.
The US rider also pushed a staggering power during his effort, holding 383 watts for the entire effort, which is around 6.2 watts per kilogram for the lightweight climber.
Valverde is now the second fastest rider on the steep climb on Strava, with a time of 19-18 after an average power of 372w (6w/kg) from the Spaniard, who weighs around the same as Kuss.
From the general classification group on stage 15, yellow jersey Tadej Pogačar was the fastest rider in the final climb, with a time of 19-32 and an average speed of 19.9km/h, compared to 20.6km/h for Kuss.
Sadly Pogačar doesn’t share his power data on Strava, but his GC rival Richard Carapaz (Ineos Grenadiers) does, as he was just one second slower on the climb than Pogačar (UAE Team Emirates).
Carapaz pushed 363w in his group to reach the summit, setting the fourth fastest Strava time in the process.
Stage 15 of the Tour also featured the highest point in this year’s race, known as the Souvenir Henri Desgrange, as the peloton took on the Port d’Envalira, 2,400 metres above sea level.
The entire Port d’Envalira segment covers 21km with an average gradient of 3.7 per cent, making it a long but gradual ascent for riders to take on.
On stage 15 the fastest time on Strava didn’t fall, as it is still held by Damiano Caruso (Bahrain Victorious) during a 2020 training ride.
Caruso’s time was 45-36, but Alexey Lutsenko (Astana-Premier Tech) was second fastest as he took on the climb in the 2021 Tour, with a time of 46-14.
Lutsenko pushed 330w for the climb.
But the real prize on offer on Envalira went to Nairo Quintana (Arkéa-Samsic), who was the first rider to crest the climb in the breakaway, winning the Souvenir Henri Desgrange.
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