At the Tour de France, bikes cannot weigh less than 6.8kg, a minimum limit set by the sport's governing body, the UCI, which applies in any race under its jurisdiction. With some of the best teams in the world struggling to ensure they're not under the limit, you might expect every bike to achieve a weight as low as 6.8kg. But that'd be far from true, despite the amount of money and engineering expertise at teams' disposal and the supposed advantage that lower weight brings. As the Tour de France meets the high mountains, only a select few riders' bikes will be at or near the minimum weight limit. As we'll explain below, this is due to bike and component sponsorship deals, specific rider roles, rider size, and greater emphasis on aerodynamics. Tadej Pogaar's Y1Rs aero bike is claimed to tip the scales at just over 7kg, thanks to shaved off paint and lightweight ancilliary components (Image credit: Aaron Borrill)Aero is still everythingWe expect to see most riders on all-out aero bikes or all-rounders that combine low weight and low drag, even on the most mountainous days. This is because they climb so fast, with the best exceeding 25km/h, that aerodynamics still trump weight as they do on flat and rolling terrain.This is more pertinent if a team can get its aero bike close to the weight limit. Jonas Vingegaard and Tadej Pogaar have exclusively raced the Cervlo S5 and Colnago Y1Rs in recent years because their teams can get these aero bikes down to the 7kg-mark in their smaller frame sizes. They seem to have calculated that this option is faster overall than riding a 6.8kg climbing bike.Aero bikes may also be better for riders whose job it is to pull on the flat or set the pace early on climbs. They need to optimise for low drag, not low weight, because they'll drop back when the pace picks up on the ascent. But a climber or GC favourite who shelters in the wheels at these points will benefit more from a lighter bike, especially smaller riders for whom the bike constitutes relatively more of their system weight (bike, equipment, clothing, body). For example, Paul Seixas is likely to continue to ride his Van Rysel prototype in the mountains while some of his teammates stay on the RCR-F aero bike. Some riders from Jayco-AlUla have access to a stripped down Giant Propel Advanced SL aero bike rumoured to meet the UCI weight limit of 6.8kg (Image credit: Aaron Borrill)One-race-bike platforms Many Tour de France teams race the same bike on every road stage. In terms of weight, if they're lucky, this will be an all-rounder, such as the Jayco-AlUla's Giant Propel, Red Bull-Bora-hansgrohe and Soudal-Quickstep's Specialized S-Works Tarmac SL9, or EF Education-EasyPost's Cannondale SuperSix Evo. These major bike brands have succeeded in making either climbing bikes more aero or aero bikes lighter, making a 6.8kg build eminently possible. At the Grand Depart, we weighed Remco Evenepoel's 52cm S-Works Tarmac SL9 complete with pedals, bottles and cycling computer fitted at 7.05kg.The trend for team leaders to get a special-edition blacked-out frame, saving 150-200g of weight in paint, makes this easier, as does the option to ditch a front derailleur and opt for a one-by drivetrain.Frame size is influential too. Movistar's diminutive climbers will be able to get their Canyon Aeroads down to 6.8kg. This will be harder for Alpecin-Premier Tech's taller Classics-style riders.Remco Evenepoel's Specialized S-Work's Tarmac SL9 weighs just 7.05kg with pedals, bottles and cycling computer fitted (Image credit: Aaron Borrill)The less fortunate teams will have one bike that may be fast but isn't that light. In previous years, Uno-X Mobility, for example, has climbed mountains on its Ridley Noah Fast 3.0, which weighs about 8kg. This year, the Norwegian team will probably ride the Belgian brand's unreleased Falcon RS climbing bike, although this might still be above the UCI weight limit. As attractive as it is, Groupama-FDJ United's Wilier Filante SLR ID2 is also likely to be a few hundred grams over the weight limit. Teams also report that their riders generally prefer to race the same bike all year round. Such tuned-in cyclists like having consistent geometry, handling, contact points and components. They usually don't consider it worthwhile to forsake all this for a slightly lighter climbing bike a handful of times a year. As aero bikes and all-rounders have become the go-to choices in the WorldTour, several bike brands have differentiated their climbing bikes through renewed focus on low weight this includes the Canyon Ultimate, Giant TCR and Scott Addict RC Pro, each of which is light and competent enough to be used in the high mountains of the final week of the Tour de France. This leaves the Scott-sponsored NSN Cycling Team with just the Foil RC for racing. Being quite an old aero bike, released in 2022, it's not the lightest of the pro peloton's do-it-all race bikes, weighing 7.28kg in size 54cm on our scales. We'd expect Scott to address the Foil's weight in the next generation, but for now, NSN is giving away about 500g to rivals whose bikes are at the weight limit. Team UAE Emirates-XRG has access to aftermarket titanium bolts and hardware from Carbon-Ti (Image credit: Aaron Borrill)Budgets and sponsorshipsThe amount of money, whether in cash or in kind from sponsorships, available to teams influences bike weight, too. The better-funded teams have the means to lower the weight of stock bikes that worse-off rivals don't. Most wheel brands these days can hit 1,300g or lower in a 50mm-deep wheelset, so teams are on a pretty level playing field regarding rims. But squads whose bike or component sponsor makes a lighter, climbing handlebar can save weight by switching from the thicker, aero bar. EF Education-EasyPost, for example, can save about 110g by changing from Cannondale's SystemBar Road to the SystemBar Road SL, which has thinner, rounded tops. The Cannondale SuperSix Evo is one of the all-rounder bikes that balances aero, stiffness and weight. Even in size 56cm, Kasper Asgreen's SuperSix Evo weighs 7.29kg (Image credit: Aaron Borrill)The biggest budget teams can go aftermarket, too. Lidl-Trek, for example, has been using $1,200 hubs to save 70g as reported by sister site, Cyclingnews while Tadej Pogaar's UAE Team Emirates-XRG is sponsored by lightweight component company Carbon-Ti. Parts such as its X-CarboRing Evo chainrings cost 436, and its X-Hanger DM integrated derailleur hanger costs 42. While these parts won't cut massive weight from the complete system, they do add up and arguably improve performance, too.The cost-to-benefit ratio of such modifications is marginal at best and well beyond the means of Cofidis or Caja RuralSeguros RGA. It goes to show that the richest teams can not only afford the best riders but also equip them with the best equipment, giving them a further advantage.