Here’s a bold statement: Lightweight bikes might not actually make you faster, and the reasons why are more fascinating than you think. Andy Turner dives into why climbing bikes are far from obsolete, and it’s not for the reasons you’d expect. But here’s where it gets controversial: could it be that we’ve been overemphasizing weight all along? Let’s explore.
This month marked the debut of the new Cervelo R5, a climbing bike so subtly redesigned that it blended seamlessly into the pro peloton for weeks. It wasn’t until journalists spotted it in a car park in Lille during the Grand Depart of this year’s Tour de France that its existence became widely known. Yet, what no one anticipated was that this would be the last time we’d see it in competition. Why? Because the recently updated Cervelo S5 dominated the scene, leaving the R5—and other climbing bikes like Colnago’s V5RS—gathering dust in team trucks. The V5RS, for instance, was overshadowed by the more aggressive design of the Y1RS, while Jayco Giant opted for the Propel over the excellent TCR for the entire event.
At the time, analysts (including us) were scrambling to understand team equipment strategies. One key insight emerged: at speeds above 26 km/h, a heavier bike (by 1-1.5 kg in some cases) could be just as effective—or even faster—if it was more aerodynamic. As speeds increase, aero advantages grow exponentially, rendering weight-saving arguments less compelling. But does this mean lightweight bikes are irrelevant unless they’re also aero? Not necessarily.
While aero bikes dominated the men’s race, the Tour de France Femmes told a different story. The race was won on the new 5.97kg R5 by Pauline Ferrand-Prevot. So, why didn’t she choose the aero-focused S5? I consulted our resident aerodynamicist, Andy Turner, for his take.
‘Pauline optimized her setup for a balance of aero efficiency and other factors,’ Turner explained. ‘She invested her weight savings in deeper wheels and positioned any unspent grams low in the frame. This gave her speed on flat sections and confidence during mountain descents due to a lower center of gravity.’ Compare this to Sarah Gigante, who struggled to make up ground in the corners—possibly due to her bike setup.
But here’s the part most people miss: when asked if a smaller frontal area (from a smaller frame) made a difference, Turner was emphatic. ‘The S5 will always be faster in pure aero terms, but with deeper wheels on the R5, the gap narrows. Other advantages can outweigh the S5’s aero supremacy, making the R5 a strategic choice.’
Within a kilo or so of the UCI weight limit, an aero-optimized approach often delivers more bang for your buck than weight saving. But there’s no one-size-fits-all answer. ‘Aero supremacy doesn’t mean weight is irrelevant,’ Turner clarified. ‘It’s just not the only factor, especially with strict limits in place. The real challenge is recognizing that weight isn’t as critical as we’ve been led to believe when compared to aero performance.’
Turner argues that consumers fixate too much on bike weight, when system weight (bike + rider) is far more significant. ‘Aero bikes aren’t heavy—most are under 8kg—and even heavier aero bikes can get close to climbing bike weights, giving them a clear advantage, especially on less hilly stages.’ Even the legendary Ventoux mountain stage fell to an aero bike this year.
So, are lightweight climbing bikes dead? ‘Lightweight benefits have often been overhyped,’ Turner said. ‘Most of us can’t feel the difference of a few grams, yet we spend a fortune chasing them. The physics is clear: those advantages rarely translate to real-world speed—they’re more about bragging rights than performance.’
And this is the part most people miss: comfort. While the new S5 and R5 share the same stack height, Ferrand-Prevot rides hers with 35mm of spacers—a compromise for power output. The R5’s seatpost and frame are more forgiving, offering a better balance of stiffness and compliance than the bulkier S5. For consumers, an aero bike’s extreme position is often impractical for casual rides. Climbing bikes, on the other hand, prioritize comfort, which is crucial for endurance and confidence, especially in corners.
Here’s the thought-provoking question: Are we sacrificing comfort for aero gains that might not even matter for most riders? For the average cyclist, a climbing bike is likely the better choice nine times out of ten. Comfort and compliance keep you on the bike longer and boost your overall performance.
While aero bikes have come a long way in terms of comfort, climbing bikes like the R5 remain the more enjoyable ride. So, before you chase those grams, ask yourself: What really matters for your riding experience? Let us know your thoughts in the comments—do you prioritize weight, aero, or comfort? The debate is far from over.
