With the return of weight marks to the spotlight and the advent of lighter bikes, the UCI’s 6.8 kg limit for racing bikes is back on the table and bringing back the debate we had years ago about whether it’s an appropriate limit or whether technology allows lighter bikes to be made while still remaining reliable.
Let’s go back about a decade. Before aerodynamics, disc brakes or internal cable routing dominated virtually every bike design on the market. A time when the knowledge of the capabilities of carbon fiber began to take off definitively and manufacturers began to use this material to its full capacity and not, as they had been doing until then, simply transferring the manufacturing systems and structures that were applied in aluminum and steel frames to carbon tubes.
From then on, the bikes underwent a leap in evolution and allowed them to be refined to the limit, a limit that the UCI was responsible for setting for competition bikes at 6.8 kg, determining, according to their studies, that with the technology of that time that was the minimum figure that a bike should weigh to be completely reliable and manageable.
It was a time when touring cyclists started to ride lighter bikes, and we even saw some weight freaks riding much lighter bikes. Even the brands were launching standard bikes that lowered that figure and that, to be used in competition, had to be ballasted to reach the minimum weight.
Who doesn’t remember the “Legalize my Cannondale” campaign with the Saeco cyclists dressed in a prison jersey in reference to the illegal weight of the Six13 model, made with a carbon main triangle and aluminum rear?
The advent of aerodynamic bikes began to make it more difficult for racing machines to approach the UCI limit of 6.8 kg as there was more material to achieve drag-reducing profiles. The widespread use of high profile wheels also contributed to this. However, what finally pushed racing bikes away from those weights was the arrival of disc brakes and fully internal cable routing, which have fattened virtually every bike on the market.
Now, however, the brands are once again focusing on reducing the weight of the bikes, without renouncing all the aerodynamic gains and technological innovations incorporated in all these years. This is possible thanks to the emergence of better quality carbon fibers, the appearance of new resins that give greater cohesion and resistance to the frames and the evolution of manufacturing processes, with more precise studies thanks to finite element simulation programs that make it possible to squeeze every gram of material by eliminating them where they are not necessary.
The result is frames with a level of lightness inconceivable just a few years ago, but not only that, also meeting stiffness or absorption parameters in line with the requirements of a racing cyclist.
Is the limit obsolete?
With all these evolutions in bicycle manufacturing technology, the question, already raised at the time, is once again whether the figure of 6.8 kg set by the UCI as the minimum weight for bikes makes any sense. The answer would be yes and no.
On the one hand, the existence of a limit puts a stop to the temptation for brands to exceed the limits. In the past, when this debate was raging it was not uncommon to test some bikes around 6 kg. If you were a light and small rider this was not a problem, but if you were a big rider it was common that riding such bikes was an exercise in technique, most of the time a very difficult task
However, at that time there were no advanced studies using FEA software and no differentiated laminates were developed for each size. Nowadays, brands give the importance to performance and all bikes have to meet certain requirements of stiffness and absorption for which each size of the bike is a different development with different laminates. That is to say, nobody is going to lighten a bike just for the sake of lightening it if that is going to mean a decrease in its qualities.
On the other hand, the UCI, as a control body, now requires that all bikes to be used in competition must be certified by them. To this end, manufacturers have to send designs and frames that are tested and verified to comply with the technical regulations before they are approved and can display the characteristic sticker that almost all frames on the market seek to show off on their seat tube.
The brands also have test laboratories, some even have scanners and x-ray machines, not only to verify that the frames they build meet the required parameters, but also to analyze when a breakage occurs to determine the cause and take corrective action if necessary.
It is clear that everything can fail and there are still bikes that break, however, a catastrophic failure, for example a fork or a frame breaking suddenly while riding is something tremendously important.
With all these evolutions and controls, it would seem that the elimination of the 6.8 kg limit should not make manufacturers go crazy with weight, especially because of the culture that performance does not depend only on weight and neither cyclists nor manufacturers are going to penalize power transfer or wind penetration just for gaining a few grams. The proof is in the bikes of the last few years where the pros have been competing with bikes clearly above 7 kg.
Source: www.brujulabike.com