We are in the carbon fibre age in cycling, at least when it comes to performance bikes. This once exotic material is now commonplace and most bike shops feature a healthy selection of carbon fibre bikes. The word graphene has been bandied about in the science world for a few years and more recently by bike companies who see graphene as the material of the future. Italian tyre brand Vittoria are riding the wave and currently promoting their new wheelsets and tyres which include a graphene compound. Let’s take a closer look at graphene, its properties, and the hype.
What exactly is graphene and why is it so special?
Do you remember lead pencils? They’re not made of lead, they’re actually graphite pencils? Graphite is a naturally occurring form of carbon which has been mined since the 16th century and, besides pencils, has been used for lubrication, in steel making and foundries, for brake linings, and more recently in batteries. Graphite is used in powder form or mixed to create compounds, such as with clay for for ‘lead pencils’. For a lithium ion battery, the anode is made from graphite and there is 10-15 times more graphite than lithium used.
Historical photo of a graphite mine in Kurnegalle, Sri Lanka
Imagine a 1 atom thick layer of pure carbon atoms in a honeycomb arrangement; this is called graphene. If you start adding layers, it is then known as graphite, though the term graphene is often used when there are multiple layers.
Illustration of the crystalline structure of graphene
The story of graphene discovery in modern science is fascinating. Graphene was predicted in 1947 (Philip R. Wallace in “The Band Theory of Graphite”) and it was grown on crystals in the 1970’s. In 2003 at the University of Manchester, Andre Geim and Kostya Novoselov isolated Graphene using ordinary sticky-tape and pencils. In essence, they used adhesive sticky-tape to attract a thin layer off the graphite pencils – extracting the minuscule amounts were a break-through and for this they won the 2010 Nobel prize in physics.
Extracting graphene with stickytape
The chemical and physical properties of graphene are what make it so appealing. For example, it is a zero-gap semiconductor – electrons move extremely fast through graphene, 200 times faster than silicon. In turn it has the lowest electrical resistivity of all known materials – low resistivity indicates that a material allows the movement of electrical charge. It is impermeable – even the lightest helium atoms can’t pass through it.
It is also strong – stronger than carbon fibre, so even less material is needed for an application, making it also very light. Futurists have already speculated that graphene sky bridges anchored to the earth could reach up into space (anchored there with a counter-weight) and be a space elevator to transport goods into space. While the space elevator may be too ‘sci-fi’ for many, graphene is a material with the properties that could make this a reality.
For bicycles, not only is graphene a lighter and stronger construction material, if it can store energy then it eliminates the need for external batteries – it can power lights, cycle computers, and even e-bike motors. And best of all, it can be infused into other materials and parts and lend them its properties.
The hype around Graphene
Graphene is still in the research and experimentation stage; the reality of real world applications will be far removed from the visions. Graphene harvesting is currently primitive and limited to minute quantities, it’s still too early for the production of commercial quantities which are required for innovators to begin research and development.
It means that we are many years away from the fabrication of graphene for structural parts. In May 2015 MIT (Massachusetts Institute of Technology) publicised a process which could take graphene creation away from the science labs and into commercial production with their demonstration of a process for producing a roll of graphene. Even this demonstration produced a ribbon thin slice at a rate of 25 millimetres a minute. And, very importantly, they are already recognising that there are different levels of quality which is significant when it comes to bikes in the future.
MIT researchers investigating mass-production techniques for graphene
Bike riders who have ridden for years are probably aware that steel, aluminium, and carbon fibre comes in different grades and quality. Likewise, bike frames or parts made of graphene in the future may have varying quality. Despite all of this, the marketers and designers aren’t holding back from taking on this trending material of the future, regardless of whether there is a noticeable current advantage to using it.
The Merida Scultura 9000 Ltd with a 680g frame and total weight of 4.56kg
In grand form, Italian tyre brand Vittoria has embraced this trend with their graphene tyres and new line of G+ wheelsets which they name Intelligent Tyre System (IT’S). In response to my query, Vittora confirmed that they use a graphene compound, however were not able to provide details such as the amount of graphene or the compound composition. In their catalogue they share the following:
Vittoria’s use of pristine Graphene
In short, Vittoria only uses the most premium form of Graphene (pristine) in order to unlock the greatest possible improvements for all our products. This pristine Graphene Vittoria uses, in comparison to other forms of Graphene, offers 4 to 6 times greater improvements for the material it is applied to (carbon for wheels, rubber for tires).
Vittoria decided to also become a shareholder in Directa Plus to stay connected to their research and development competence, which is needed to be a part of the most advanced material research.
While, on the one hand, they want to protect their trade secret from competitors, it does make it extremely difficult for externals to judge any advantage. For their tyres, Vittoria claim that their Corsa Speed (tubeless) has 40% less rolling resistance and that independent testing (by Wheel Energy in Finland) confirms that over a 50km Time Trial that their wheel is 32 seconds faster than their closest competitor. Whether this is directly due to the graphene, or to other technology, is unknown.
Vittoria’s comparison graph
The practicality of graphene in cycling
If science can advance graphene production so that it can one day be used for bicycle fabrication, we will likely see two approaches. The first is graphene composites. This is what Vittoria has done and is similar to the concept used in carbon fibre composite materials, for example the soles of cycling shoes are often a composite, likewise the carbon fibre housing for bike parts. With this approach, the ‘graphene particles‘ enhance the composite.
The second approach, the one we are all dreaming of, is wafer-thin bicycle frames. As with carbon fibre, the graphene sheet will also needed to be bonded with a resin to provide the re-enforcement so that it can retain its structure. However a bike frame material from a one-atom thick graphene layer will not only be translucent, it may be impossible to manufacture. It would take 3 million sheets of graphene stacked to have the same thickness as one human hair.
There has been speculation that graphene could be produced in strands and woven, the same way that carbon fibre is woven into sheets. Similarly creating composites is a very likely approach – for example carbon fibre enhanced with graphene. Researchers across the globe and at the University of Wollongong, have been able to create graphene yarn.
We will likely see the automotive industry lead the push. If a fabricated graphene part can be made, you will probably spot these first in Formula One racing. The obvious part is the chassis but graphene can make its way into all working parts and even take over the electronics, which would eliminate the kilometers of cabling typically required.
The energy storage capabilities is particularly interesting for e-bike manufacturers. If the frame itself were to become a light weight integrated storage, it not only will substantially drop the weight of e-bikes, it will also make mechnical-doping a real threat in competitive cycling.
Yes, it is light and strong, but what about flex? The ability to design compliance in carbon fibre bikes is crucial for rider comfort. The wealth of new graphene products coming onto the market, including flexible sheets and foams, suggest that any hurdles on the horizon will be overcome.
It is unfair to give graphene all the glory without any reference to carbon nanotubes (CNT), which are tubes of carbon atoms. The carbon nanotubes can be created in a number of different processes of controlled chemical reactions, and researchers at Rice University in Houston, USA have succeeded in creating carbon nanotubes which are hundreds of meters long.
Even stronger than graphene, carbon nanotubes are also elastic so can lend some attractive properties to carbon fiber bikes. Typically, short carbon nanotubes are available commercially in the form of a powder and in industry are usually an additive in resin to improve the properties of the ‘product’. However, since 2005, sheets of carbon nanotubes are being produced commercially comprising of short 1mm carbon nanotubes. A close relation of carbon nanotube are carbon nanofibres which are similar, though often larger and inherently have more defects.
Nanocomp Technologies with a 122 metre carbon nanotube (CNT) sheet
There is significant interest and R&D in utilising carbon nanotubes by both aeronautical and military companies and organisations. Spanish bike accessory company Catlike have used what they call graphene nanofibres in their 2014 Mixino helmet. Exact detail are unavailable and it is noted by Catlike that they ‘treat’ the synthetic (Aramid) roll-cage which lines the helmet inner with the graphene nanofibres.
The London Times newspaper featured an article titled “Catlike brings graphene to the peloton” and called it a miracle material. Like Vittoria – the marketing message is appealing, though it is still difficult to judge the actual value.
Milking the graphene cow
The cycling industry is like many others – when there is something new on the horizon it is the opportunity to sell more and the marketers will be out in full-force. Just like the introduction of carbon fibre into cycling, graphene will get better and cheaper over time. There will also be a lot of misinformation and unknowns – for example do we know the effect of carbon fibre under constant UV exposure?
Graphene is exciting, but is one of the many miracle materials of the future waiting to be unleashed.
Mining Graphene: Public Domain
Graphene Structure: Core Materials
Extracting Graphene: Gabriel Hildebrand (public domain)
Space Elevator: Obayashi Corporation of Tokyo, Japan/Japan Space Elevator Association
Carbon Nanotube Sheet: Nanocomp Technologies