I’ve been trudging through marketing waffle from Vittoria waxing lyrical about their use of the latest super material Graphene in their uber rubber tyres.. Basically is says Graphene is ace for making tyres hard wearing yet super sticky.

Because Whenever a new claim of superiority is made is have to ask the dull questions of How and Why, I’ve also been researching other rubber tech and apparently (according to the OECD) carbon nanotubes and rubber nanotubes are doing similar things as this new use of Graphene.. So I read an insight into Conti black chili compounds, and how they work. (I know, I am a nerd)

Basically it seems all these guys are making rubber that changes properties depending on friction and heat produced when used, I.e. A bit akin to the old specialized Epic Brain technology was. This means that in a straigh line at constant speed the rubber is boringly hard, as it’s not got much to do, yet when the rider brakes hard or starts cornering hard they impart serious friction into the rubber, which in turn creates heat and changes the molecular properties to turn the previously hard rubber into soft sticky rubber..

Is it really as stupidly simple as that when you ride hard your tyres melt?
Or is it equally as stupid that (like specialized brain suspension was) the technology is only turned on after its first needed, and thus when you need to do a sudden emergency brake, the wheel has to roll a full circle before the rubber gets grippy?

(These things keep me awake)

It could also just be a lot of marketing BS?

I’m a materials scientist! I know nothing about the brain suspension system though. I saw Vitoria’s claims too, and thought that it sounded like BS.

Rubber is a funny material to work with. From a mechanical POV, its behaviour changes according to temperature, strain, strain rate and the application environment. This will affect things like the contact area, spring rate, rolling resistance and friction behaviour.

Natural rubbers are typically reinforced with particulate (and sometimes agglomerated) carbon black. Basically, lumps of carbon. It is dispersed throughout the rubber to make it stiffer amongst other things. I would expect that carbon structures like tubes would have a similar effect if embedded in rubber. So, the graphene may make it stiffer, but i can’t say whether it would be more or less so than good old carbon black.

Carbon black also provides UV protection. I don’t know if graphene can do this for the tyre. Good UV protection means that the tyres will last longer in sunny places.

in a straight line at constant speed the rubber is boringly hard, as it’s not got much to do, yet when the rider brakes hard or starts cornering hard they impart serious friction into the rubber, which in turn creates heat and changes the molecular properties to turn the previously hard rubber into soft sticky rubber..

If you’re riding on a flat, ideally smooth surface with an equally smooth tyre, the tyre deformation will be minimal. Hpwever, there will be some deformation which will heat (by working) the tyre and adjust its mechanical behaviour. In the real world, your tyre is deforming against loads of microscale contact points(asperities) across the contact area, thus it is getting hotter during deformation and cooler when undeformed . The rate of temperature change will depend on the thermal conduction behavior of the rubber and the environment it is in. As the tyre temperature changes, the internal friction of the rubber will change leading to change in the tyre performance (hopefully to the better!).

Lastly, the tyre architecture should be considered (casing, bead, tread profile, multiple rubber compounds). If Vittoria have got that perfected, along with the material, and can prove that graphene offers significant improvement over cheap carbon black, then I’ll listen :0)

cheers HansRey – useful info their thanks. so what I’m struggling with is the rate of adaption that a rubber tyre can make to react to the instant changes in need of the rider. when we talk about tyre temp changes, I think of those as gradual (i.e. taking seconds, not a fraction of a second) and not instantaneously as a rider needs it to be. in my mind it’s complicated by various factors, the first being the rotation of the wheel, where a patch of tyre rubber is only in touch with the surface for a brief moment as the wheel spins, so it doesn’t have time for that patch of the tyre to react. The second is that unless the wheel is spinning super-fast then the cooling effect of the air will have neutralised any effect. so for car tyres, this tech makes a lot of sense due to the mass of the vehicle and the speeds involved producing significant heat on the contact point. but for bike tyres, with lets say 12 stone rider and a lightweight bike this feels like unless your hammering down the side of an Alpe, then it aint gonna happen.

(btw – the point of the Specialised Brain, was that they used a brass actuator that sat on top of the oil valve that effectively shut-off the oil valve and stopping the suspension shock from moving, but when you bit a bump the brass actuator was bounced off the valve, opening the way for the oil to flow and the suspension to do it’s thing, the thing was locked out on smooth sections and great once you were about 10yrds into a rock garden and the brain valve had opened, but for those first 10yrds you basically had a hardtail with added weights and being kicked up the arse)