The 6.8kg Limit
6.8 is one of those numeric constants that every cyclist is familiar with. It refers to the 6.8 kilogram minimum weight limit set by the UCI which restricts all bikes used in competition to this weight. This regulation was established in 2000 as a means to ensure manufacturers don’t push the structural integrity of bikes and so that teams are competing on a relatively similar machines. Thirteen years later and progress made in materials engineering, riders are still bound by this rule while competing. We take a look at the reasons behind this seemingly outdated rule, how manufacturers and teams are getting around this, and how it might change in the future.
You might remember Cannondale’s “Legalize my Cannondale” campaign back at the 2004 Giro (which Cunego won) when their Six13 bikes weighed less than 6.8kg and they put weights on the outside of the toptube to showcase their featherweight bicycle that was winning the Giro (in fact only their 50cm bike achieved this weight and it wasn’t the lightest bike on the market – but clever marketing indeed).
A decade later the world’s lightest bike is said to be a staggering 2.7kg (6lbs) and while this is certainly pushing practical limits, it illustrates what can be achieved with today’s materials.
The 6.8kg weight limit has been questioned, debated, and reconsidered throughout the past thirteen years, but it now seems to be outdated to the point of absurdity. At the Tour de France we noticed many team mechanics adding weight to rider’s bikes in order to meet the minimum weight limit. They would put a couple hundred grams of fishing weights in the seatposts, handlebars, or chainstays to boost the weight up to 6.8kg. And while the bikes were certainly top-end, they weren’t using exotic materials nor trying to be a weightweenies bike.
Perhaps the most overused buzzwords in the manufacture’s marketing dictionary for each new product release is “lighter”. In most brand’s flagship bikes the 6.8kg limit is easily surpassed without necessarily trying to push that limit. Commissaires don’t often check bike weights at the amateur level, but recent examples from the Tour de France (on Alp d’huez) and the Giro Rosa (Fabiana Luperini, the five-time Giro champion’s bike was 100g under the limit and was disqualified) shows that the UCI does in fact take this rule very seriously.
If bikes need to have dead weight added to them for the sake of this rule, we naturally question what today’s rational is behind this rule and if it’s being revisited.
We asked UCI Technical Collaborator Johan Kucaba if the UCI still believes that a bike lighter than 6.8kg poses a significant safety risk to riders. He explained:
“The rule 1.3.019 has been introduced and has been created as many other rules of the UCI Technical Regulation by an ergonomist expert in cycling. This specialist, with the advice of other experts, has defined that 6,8Kg is the minimum weight acceptable for a bicycle, for an essential reason that is the manoeuvrability of the bicycle. Of course, technical risks related to composites materials have also been considered, but the primary reason of this rule is the manoeuvrability. We therefore believe that bicycles of 5 Kg (for example) pose significant risks of manoeuvrability.”
What does “manoeuvrability” refer to? Mr Kucaba further explained:
“Manoeuvrability is the property of the bicycle has to be driven properly, correctly. We all know that different bicycles offer different performance, particularly in terms of manoeuvrability, and we believe that a bicycle of 5Kg would be very bad even dangerous to manoeuvre, to drive. The weight has a role in manoeuvrability of a bicycle because it mainly brings stability to the bicycle. The UCI is therefore concerned about it because the safety of the riders would be directly affected.”
UCI technical specification doesn’t refer to manoeuvrability, but the UCI tells us that they will be updating it. However, it does seem fairly arbitrary that the original goal of a weight based on safety happens to be the same as manoeuvrability.
We spoke with SCOTT’s Chief Engineer Benoit Grelier and asked him this thoughts on materials progression and if we’re at the point where sub-6.8kg bikes are safe enough and manoeuvrable enough to be ridden in professional races. He explained,
“Yes, absolutely. Have a look at the Addict SL: without resorting to exotic parts (the bike is assembled with Ritchey, Sram, Syncros components), we can go down to around 6kg for a complete bike.”
Of course there is nothing that says that manufactures cannot produce a sub 6.8kg bike and sell it like that. The UCI certification stickers only certify that new frame/fork models are in accordance with the requirements of the UCI Regulation for racing. It says nothing about the weight of a complete bike. Engineers will build their frame and forks as light as possible which also meets their strength and stiffness targets and don’t attempt add extra weight to reach a certain limit. The minimum weight limit will be left to the complete build, which will always vary.
Jürgen Falke, Merida’s Director of Products told us,
“We could potentially bring the frame-weight down about 100-150 grams from todays level – and today’s level is already extraordinary for a mass-production frame-set (our Scultura SL frame weighs 840 grams in a medium size, including rear derailleur hanger/seat-clamp). At 750 grams, the border for a reasonable mass-production carbon-frame is reached. There is not that much space there. A real 700 grams can be just reached with “clean-room environment” as Cervelo is doing it with their CA models – but is an unreasonable effort to squeeze-out the last 50 grams.”
“At such considerations, everyone need to keep in mind that the major part of the bike-weight is created by the specs, not by the frame-set. A SRAM RED group weighs less than a Shimano Di-2 – but the shifting performance of Shimano is the benchmark. Wheel-sets are a huge-factor for the overall-weight – but just some specialized brands offer workable sub 1 kilo wheel-sets.”
But the UCI isn’t so confident. Mr Kucaba said:
“We are aware that technology and materials evolve, and it would be comprehensible to think today that from a technical point of view, this weight limit could be lowered. But we have no assurance that bicycles of 6Kg (for example) are safe. We have in our Equipment Commission an engineer specialist of cycling, who worked for many manufacturers and who have designed several bicycles that are still in the peloton. This engineer expert in composite materials is not completely convinced of the reliability and strength of the bicycles weighing about 6Kg. We know that some bicycles of less than 6,8 Kg are commercialized and that some manufacturers think they are safe. We also have feedbacks from many other manufacturers who don’t think the same thing, and who advise us to leave this 6,8Kg weight limit, because this limit is very accurate and that it prevents an unreasonable race to the minimum weight.”
Where to from here?
When we ask engineers if they think the weight restriction should be revisited, Benoit from Scott said:
“If the current limit of 6.8kg is selected to ensure the safety of the bikes for the riders, then the rule should be revised. We can build a bike of 7.2kg which will be dangerous to ride, and a bike of 6.0kg which is strong enough for all races. Take a lightweight frame, assemble it with heavy, strong wheels, and use a lightweight exotic handlebar… Your bike weights more than 6.8kg, but don’t go for a sprint with it! From our experience, a frame and fork combo of less than 1kg does not compromise on safety or handling, because we surpass the highest level of testing at EFBe, and reach our stiffness targets. Giving a weight limit for the complete bike does not ensure the safety of the bike. Strength and Fatigue tests for each bike part does. However, as I already had the opportunity to mention to the UCI, if they would like to go in this “testing” direction in place of the current weight limit, the UCI should use the existing norms and tests to define their rules, and discuss with the bike industry. They should not create another “UCI” standard, which would lead to a huge increase of the development time and costs, slow down the industry and kill smaller brands.
Jürgen Falke from Merida adds,
“At the UCI MTB XC circuit, there is not such a rule and the MTB’s have to pass even higher demands in loads than a road-bike. There will be an natural border, where the stiffness and durability (f.e. at wheels) will drop, when undergoing a certain weight-level. This is up to the racer (or his team-managers), if they accept to risk higher defects.
“My personal conviction is that weight-saving is over-estimated and aerodynamic quality has to be improved. It will be the bigger challenge, to lower the aerodynamic drag at frame and wheels, without adding weight compared with todays 6,8!”
The UCI is hesitant to relax this rule however. Until they get assurance that bikes weighing less than 6.8kgs, especially to maintain sufficient manoeuvrability, “we still believe currently that the weight limit of 6,8 Kg is appropriate and accurate. This limit will not be deleted or modified for the moment,” they explained.
In terms of what type assurance they’d need, with which they responded: “In order to have the weight limit lowered, it would be necessary to give technical proof (scientific and technical studies, opinions of riders, results of tests) that a bicycle of less than 6,8 Kg is safe, and provide scientific proof that a bicycle under 6,8 Kg provides sufficient and accurate manoeuvrability to the rider. If all these proofs are provided to the Equipment Commission, then it could possibly decide to modify or remove the weight limit.”
The UCI Equipment Commission meets two times per year and are aware that this is an important issue and is regularly discussed. No matter what the limit is set to, engineers, manufacturers, and aficionados will push the limits of their bikes to make them as light as possible. It’s what we do.