More riders are using single chainrings than ever before at the 2026 Tour de France, as the 1x (or one-by) trend spreads beyond time trials to road stages. The 2023 Tour de France was the first at which major teams, including Lidl-Trek and Visma-Lease a Bike, went 1x for flat and mountainous days. One-by configurations have been popular during the Spring Classics, and we saw this used liberally by teams at Opening Weekend given the relatively flat terrain on offer and higher average speeds. One-by drivetrains involve replacing a traditional double chainring set-up with a single ring, usually with a narrow-wide profile and sometimes with a chain guide for chain retention, and removing the redundant front derailleur. A larger-than-usual cassette normally compensates for the loss of gear range, to help riders find the right gear. One-by configurations have become popular choices across the season, most notably at the Spring Classics where flat, fast terrain makes it an easy decision to use (Image credit: Aaron Borrill)It was no coincidence that both the teams adopting the tech are sponsored by SRAM. The American brand officially supports 1x on the road, unlike Shimano, where teams tend to use 2x exclusively. Even Mathieu van der Poel, riding for Shimano sponsored AlpecinPremier Tech and usually running a double set-up at races dominated by 1x like Paris-Roubaix, has used a single chainring at this year's race. Campagnolo has introduced single road chainrings, but has just one team at the Tour de France - in wildcard squad Confidis - and no WorldTour squads.In addition to Visma-Lease a Bike and Lidl-Trek's continued use of 1x, SRAM teams such as Uno-X Mobility and Pinarello Q36.5 have joined in for certain stages in 2026. However, that's not to say double chainrings are on the way out. The extra range they provide makes 2x the best all-round option. And stage six's Tourmalet day, where Pogaar put minutes into Vingegaard while running larger chainrings, exposed the limitations of the Dane's 1x approach in the eyes of notable observers, such as the 2017 Giro d'Italia champion Tom Dumoulin. We asked Xavier Disley, PhD, the director of AeroCoach, who advises some of the world's best cyclists on how to go faster, about the pros and cons of single chainrings on the road. Tom Pidcock is known to use a one-by configuration in combination with a traditional SRAM Red AXS rear derailleur and 10-33T cassette (Image credit: Aaron Borrill)Why we're seeing more single chainringsOne of the key reasons why 1x is becoming more popular at the top of the sport is SRAM's increased presence, as we noted in our overview of which teams are riding what at the 2026 Tour de France.The Illinois-based company introduced single-ring road drivetrains as far back as 2015, with Force 1 and Rival 1. Since then it has ensured that its road groupsets work as well with front derailleurs and double chainrings as without, by adding tension to its rear derailleurs for increased chain security. It also has a line of pro-level SRAM Red AXS Aero chainrings, whereas Shimano does not yet make an equivalent. For even more range, riders can combine a large SRAM single-ring with a Red XPLR AXS rear mech and cassette from the brand's gravel line-up, as we've seen Mads Pedersen do at hilly one-day Belgian races. SRAM-sponsored teams also say that SRAM's technical support is very good at educating mechanics on how to use its intercompatible components. Until Shimano releases single-ring road chainrings, teams that receive or buy groupsets from the Japanese brand will have to buy and bodge 1x set-ups if their contracts allow. Tim Wellens has been seen running a one-by Carbon-Ti single chainring at times this season, and Netcompnay-Ineos also used one-by Drag2Zero chainrings with Shimano XTR rear mechs at Paris-Roubaix - so rider interest is there.At this year's Paris-Roubaix, Joshua Tarling, Artem Shmidt, and Ben Turner paired one-by Drag2Zero chainrings with Shimano XTR Di2 M9250 rear derailleurs (Image credit: Future)Aero advantageThe lack of a front derailleur and inner chainring makes 1x a little more aerodynamic. "It's a definite advantage," says Disley. "If you have two equally powerful riders, one on 1x and the other 2x, the first will win the sprint every time."At speeds more attainable to amateur cyclists, the 1x benefit is only a watt or two, but this scales up to three to four watts at speeds of 60km/h and above that pro sprinters reach. A larger chainring can help keep you in the middle of the cassette, which ups drivetrain efficiency by reducing chain articulation. But Disley says this is outweighed by lower drag."Aerodynamics becomes much more of a resistive force the faster you go," he says. "So drivetrain efficiency becomes less important."Whereas if you're going really slowly, aero drag isn't very much and so you should look at things like gravity, rolling resistance and drivetrain efficiency. "When you're travelling at 60km/h an hour, the only thing you really should care about is your aero drag."UAE Team Emirates-XRG's Tim Wellens, has also tried his hand at one-by, converting his 2x Shimano Dura-Ace Di2 setup with the help from Carbon-Ti (Image credit: Aaron Borrill)Lower weightIn the UK hill climbing scene, weight weenies run single chainrings to save weight. Tour de France pros could be motivated by the same rationale on climbing days. Going 1x on SRAM Red AXS drivetrain could shed about 200g 157g from the front derailleur and battery, 78g from exchanging integrated double chainrings for an aero single ring, plus roughly 30g to add a chain catcher. That's not a dramatic amount, but it's enough to get aero bikes, which the GC favourites tend to ride every day, closer to the 6.8kg UCI weight limit. "It won't help that much," says Disley. "Taking a kilo off would make a decent difference, but again, not an awful lot and 200g is just a fifth of that."Pogacar of UAE Team Emirates XRG, Vingegaard of Team Visma-Lease a Bike and Evenepoel of Red Bull-BORA-hansgrohe pictured in action during the stage 10 of the 2026 Tour de France (Image credit: Getty Images)The argument against 1xCritics of 1x say the bigger jumps between gears disrupt your cadence. This is true if having only one front ring obliges you to fit a wider-range cassette, such as SRAM's 10-36T.After Jonas Vingegaard used what appeared to be a 50T or 52T 1x chainring and a 10-36T cassette on stage six over the Tourmalet, Tom Dumoulin criticised his equipment choice. On the De Avondetappe show as reported by IDL Pro Cycling, the Dutchman said 1x would have left Vingegaard in a harder or easier gear than desirable on the climb.At flat Classics races, we'll sometimes see riders reduce these gear jumps with a tighter cassette, but this seems less common at the Tour, perhaps because riders need to save their legs for days to come. Sprinters on SRAM-sponsored teams like Decathlon CMA CGM's Olav Kooij have been optimising for sprints with a 56-tooth single ring and 10-36T cassette. On the other hand, a Shimano-equipped sprinter like Tim Merlier has been running a 56/44T double and an 11-34T cassette. That gives Merlier an easier bottom gear to get over a climb before the sprint."Climbing on a 56-tooth single an hour into the race might be a bit of a pain," says Disley. "But generally speaking, these riders are able to accommodate that quite happily."After getting over the hills, they have that aero advantage in the sprint, and having a 10-tooth sprocket gives you a bit of an advantage in terms of top-end speed over an 11-tooth."Some riders go to the extreme and pair a one-by chainring with a SRAM Red XPLR AXS rear mech and cassette from the brand's gravel line-up. This allows for greater bail-out gearing in punchy terrain (Image credit: Aaron Borrill)Did gearing efficiency cost Vingegaard?Dumoulin might be on to something here, due to the difference in steps on a SRAM 10-36T vs Shimano 11-34T cassette. On this SRAM Red cassette, the four lowest sprockets have a one-tooth difference. You skip the 14T and have two-sprocket differences until you get to the 21-tooth cog. From there, you have a three-tooth difference to 24 and then fourth-tooth steps (24-28-32-36). By contrast, Shimano's 11-34T skips up three teeth between cogs 21 and 30, then a final fourth-tooth step to 34. At higher climbing speeds of 30km/h, Vingegaard would be lower down the cassette, where the jumps are smaller. But on the Tourmalet, where his rival averaged 23km/h, he would have been experiencing fourth-tooth steps. "On Shimano, when you're climbing in the inner ring, and you're on the 17/19/21, you've only got a two-tooth change in between gears," says Disley. "That's only going to cause a six or seven-revolution change in cadence.Until Shimano releases single-ring road chainrings, teams that receive or buy groupsets from the Japanese brand will have to buy and bodge 1x set-ups if their contracts allow (Image credit: Aaron Borrill)"But if you're in a massive SRAM single chainring, a 50T or 52T, at the top of the cassette you've got a four-tooth change between gears. That's double what you have on Shimano and changes cadence by 11 or 12 RPM. "At a crucial moment in the race, that could cause you to become incredibly overgeared and unable to pull away, or being so undergeared that you can't jump away because you can't spin fast enough."We'll never know whether this applied to Vingegaard. The gap that opened might have been purely down to his legs, with watts per kilo being the decisive metric on climbs. But those larger jumps between gears at the top of the SRAM cassette might not have helped. Vingegaard's single chainring wouldn't have limited him on the descent, though. With a 52-10T hardest gear versus Pogaar's 54-11T, he actually had a slightly harder gear and the potential for higher top-end speed, although his smaller chainring would have been marginally less efficient.Visma-Lease a Bike defended its tech choices, pointing out that Vingegaard has ridden 1x multiple times, including to win this year's Giro d'Italia and beat Pogaar at the 2023 Tour. But since Vingegaard needs all the help he can get against the unstoppable Slovenian, it will be interesting to see whether his team reconsiders his gearing for the upcoming mountains.