No matter how vicious the gradient or how gruelling the sustained uphill effort, Tadej Pogačar has ridden a Colnago Y1Rs aero bike in every stage of the 2025 Tour de France, including an unpainted version to victory in the stage 13 mountain time trial. Even after his high-speed crash on stage 11, which left him with a wounded forearm and must surely have impacted his recovery, he attacked 12 kilometres from the summit of Hautacam the following day and finished more than two minutes clear of Jonas Vingegaard – exactly where he lost the Tour to his Danish rival in 2022. As he crossed the line he took his hands off the aero-optimised gull-wing bar to raise his uninjured right arm and point his index finger into the sky. That was his third stage win and the uphill TT was his fourth – is he going to carry on winning in the high Alps on a bike designed for aerodynamic efficiency and high speed on the flat, and which is around 400 grams heavier than the UCI's 6.8-kilo minimum weight limit? Has he abandoned the lightweight aero all-rounder, the Colnago V5Rs?
It might be convenient to assume that he’s so strong he’ll win whatever bike he rides. That his arm was wounded but his confidence was 100% intact and the Y1Rs’s 400 grams or so over the 6.8kg UCI minimum weight limit doesn’t hinder him. But, until the Tour de France, he appeared to favour the all-rounder V4Rs and its successor the V5Rs – which weighs 6.8kg – over the more aerodynamic but heavier Y1Rs, which launched last December. He used the Y1Rs in the UAE Tour in February, riding it to two mountaintop stage victories. But when things got serious for the Classics season he reverted to the V4Rs, winning Strade Bianche and the Tour of Flanders on it. He then rode its successor, the V5Rs, to victories at Flèche Wallonne and Liège-Bastogne-Liège. He used both the V5Rs and the Y1Rs for the Critérium du Dauphiné. So why has he ridden the Y1Rs exclusively for every road stage in the Tour de France, including his 100th pro win on stage four and a second win at Mûr-de-Bretagne on stage seven and the win at Hautacam on stage 12?
Although Pogačar's bike choices have been hogging the headlines, he’s not the only rider to be opting for his bike sponsor’s aero bike over the lightweight climbing bike. Jonas Vingegaard finished in second place at Hautacam on the Cervélo S5, the aero model from the Canadian brand that he too has been riding for the entire Tour this year. Like the Colnago Y1Rs, it weighs around 7.2kg. He has the option of the latest R5, as yet unreleased, which was ridden on the Hautacam stage by his Visma-Lease a Bike team-mate Matteo Jorgenson.
For a quick recap on the relationship between aerodynamics and weight, aero specialists Swiss Side explain: “In cycling, the biggest force working against you is aerodynamic drag. This is especially true on flat and rolling terrain, where drag can account for up to 90% of the resistance a rider faces. Weight only becomes a significant factor during steep climbs. However, even on hilly routes, aerodynamic efficiency often plays a larger role in overall speed and performance.”
Intriguingly, in 2022 when Vingegaard finished over a minute ahead of Pogačar he chose the R5. His winning speed was 35.8kph; that stage from Lourdes to Hautacam contained 4,036 metres of climbing over 143km. In 2025 the stage from Auch to Hautacam was 180km long with 3,794 metres of climbing and Pogačar’s winning average speed was 41.5kph. How much difference does the speed, distance and elevation make? Is there an equation?
According to Swiss Side: “At speeds above 15kph, drag overtakes weight as the primary resistance. Real-world testing shows that riders on slightly heavier but more aerodynamic bikes often outperform those on ultra-light setups.” Further, the brand says: “Your position accounts for the largest share of drag. Focus on achieving a low, streamlined posture… Invest in aero wheels to minimise turbulence and leverage effects like sailing in crosswinds. Wider, aerodynamic tyres with low rolling resistance can improve both speed and comfort.”
Swiss Side obviously has a vested interest in pushing aerodynamics – it makes aero wheels, cockpits, apparel and other components, and partners with pro teams such as Decathlon-AG2R La Mondiale to develop bikes, but the numbers are indisputable. In terms of the gradient, the ‘tipping point’ between aero and lightweight is estimated by Swiss Side to be around 7.5% for the pros – the gradient at which low coefficient of drag (CdA) gives way to low weight.
In the case of the 2022 and 2025 Hautacam stages, one of the possible scenarios is that the projected average speed for the 2025 stage was higher than it had been in the 2022 version (despite both finishing at Hautacam) and so the majority decided they could save more strategic watts by using the aero bikes. The dynamic of the stage was certainly more aero orientated: for the first 100 kilometres until it reached the initial slopes of the Col du Soulor the profile was relatively flat, and the breakaway averaged just under 50kph with the peloton at two minutes riding at the same speed. Jorgenson, who was on the R5 climbing bike, was dropped once the race hit the Soulor and lost 10 minutes and five GC places. His bike choice can’t be blamed entirely of course.
To further complicate things, it’s unlikely that all the teams use the same metrics to decide whether riders should use the aero or lightweight bikes. Discussing Decathlon-AG2R La Mondiale and their choice of bikes, Van Rysel engineer Louis Defaut says: “You will see in the Tour that the domestiques will use only the RCR-F aero bike and the fastest helmet and clothing that helps them protect the leader. The leader for the final climb will use the [RCR] climbing bike, the climbing helmet, the most ventilated jersey.” As Default said, the team’s GC leader Felix Gall finished fourth on the Mûr-de-Bretagne stage riding the Van Rysel RCR climbing bike rather than the aero bike whereas the winner, Pogačar, used the Colnago aero bike. Earlier in the season, Pogačar used the lightweight Colnago for the Classics, whereas for Paris-Roubaix all except one of the Decathlon riders used the aero bike.
Is individual rider preference for the aero or the climbing bike a factor? The geometry of the Colnago Y1Rs is slightly different from that of the V5Rs – the aero bike has slightly steeper angles for a more aggressive rider position. It’s the same story with the Cervélo S5 versus the R5. It’s likely that pros who spend multiple hours training and racing on the same bike become highly attuned to its geometry, so it's possible that it's taken Pogačar most of the season to become fully comfortable and optimised on the Y1Rs. And now that he is, he's unwilling to switch back to the V5Rs even if the physics says that on a steep gradient there might be a small gain for the same power.
Additionally, there are very few moments when a rider such as Pogačar's speed drops below 15kph. In the stage 13 uphill time trial with its gradients up to 16%, his average speed was above 28kph. In his post-race interview while warming down, he said the choice of bike was "one of the biggest decisions" – and the choice was not between the Y1Rs and the V5Rs but between the Y1Rs and the TT bike.
In a feature on Colnago's own website, UAE Team Emirates-XRG rider Rui Oliveira says of the Y1Rs: "I think this bike really shows its strengths on rolling or flat courses... but it's on the flats that it's almost mind blowing: once you're over 45kph you feel it begin to glide, almost as if it's floating. Personally I find it performs well even on moderately steep climbs." He's then asked if he can be more specific. "I'd say up to 7 or 8 per cent gradients, I don't feel at a disadvantage compared to a pure climbing bike. Even on steeper pitches if they're short – say 5-10 minutes long – it still makes sense to use it. you know you'll recover faster on the descent and in the fast sections afterwards thanks to how aerodynamic it is." This last bit is a handy reminder that what goes up also comes down – unless it's a mountaintop finish or an uphill time trial.
We reached out to Colnago and Cervélo to ask whether they could tell us how the decisions are made, but neither has responded. It seems likely the teams do not want to divulge how they and their riders decide which bike to use – it’s one of those secrets that teams can weaponise.
So are we going to see the aero or the climbing bikes on the start line of the remaining mountain stages? We won’t know until we get there – and it’s all part of the game. But so far the deeper tubes and extra grams are winning.
