The debate over Jonas Vingegaard's 1x drivetrain choice on the Tourmalet has sparked an interesting discussion about the pros and cons of single chainrings in professional cycling. While SRAM's increased presence and the aero advantage of 1x are compelling arguments, there are also valid concerns about cadence disruption and gear efficiency. Here's a deeper dive into the topic, with a focus on the implications for Vingegaard's performance.
SRAM's Dominance and Aero Advantage
SRAM's single-ring road drivetrains, introduced in 2015, have gained popularity due to their compatibility with front derailleurs and double chainrings, as well as their pro-level SRAM Red AXS Aero chainrings. The lack of a front derailleur and inner chainring makes 1x slightly more aerodynamic, providing a definite advantage in sprints, especially at speeds above 60km/h. This advantage scales up to three to four watts, which can be crucial in high-stakes races.
However, the trade-off is a larger chainring, which can help keep riders in the middle of the cassette for better drivetrain efficiency. But as Xavier Disley, PhD, explains, aerodynamics become a more significant resistive force at higher speeds, making drivetrain efficiency less important. So, while 1x may offer an aero advantage, it's not the only factor to consider.
Weight Savings and Cadence Concerns
The weight savings of 1x are also noteworthy, particularly for hill climbing specialists. Removing the front derailleur and battery, and replacing the double chainrings with an aero single ring, can save around 200g. This might not seem like a lot, but it can help GC favorites stay within the UCI weight limit. However, the argument against 1x also includes concerns about cadence disruption.
Critics argue that the larger jumps between gears on 1x can disrupt a rider's cadence, especially when using a wider-range cassette like SRAM's 10-36T. This was evident in Tom Dumoulin's criticism of Vingegaard's equipment choice on the Tourmalet. The difference in gear steps between SRAM's 10-36T and Shimano's 11-34T cassette can cause more significant cadence changes, which could impact a rider's performance, especially in crucial moments.
The Tourmalet and Gear Efficiency
The Tourmalet stage, where Vingegaard's 1x approach was scrutinized, highlights the importance of gear efficiency. On the SRAM Red cassette, the four lowest sprockets have a one-tooth difference, leading to larger jumps between gears at the top of the cassette. In contrast, Shimano's 11-34T cassette has smaller jumps between gears, causing less disruption in cadence.
At higher climbing speeds, Vingegaard would have been lower down the cassette, where the jumps are smaller. However, on the Tourmalet, where his rival averaged 23km/h, the larger jumps on the SRAM cassette could have impacted his performance. Disley explains that these larger jumps can cause a rider to become 'overgeared' or 'undergeared', affecting their ability to pull away or jump away.
Conclusion: A Complex Decision
The choice between 1x and 2x is a complex one, with various factors to consider. While SRAM's dominance and the aero advantage of 1x are compelling, the potential for cadence disruption and gear efficiency issues cannot be ignored. Vingegaard's team, Visma-Lease a Bike, defended their tech choices, citing his success with 1x in previous races. However, the question remains whether they will reconsider his gearing for the upcoming mountainous stages.
Ultimately, the debate over 1x vs. 2x is an ongoing discussion, and the right choice depends on a rider's specific needs, preferences, and race conditions. As the sport evolves, it will be fascinating to see how these drivetrain choices impact the performance of professional cyclists.
