Rubber side down
Do you want harder or softer rubber in a tyre? And which is the best tread pattern? The answers are not as obvious as one might think
Inner tubes aside, tyres are the component on your bike that you probably change most often. And when you consider that they can have a significant effect on the quality and safety of your ride, it makes sense to get the right ones. But with so many options out there, how do you make your choice?
‘Asking someone “What is the best tyre?” is a bit of a “How long is a piece of string?” question,’ says Dave Taylor of Schwalbe UK. ‘The first thing to establish is what your priorities are. Is it speed, puncture protection or comfort? Most people tell me they want a bit of each, but in reality that’s hard to achieve. There usually has to be compromise somewhere. Having maximum grip often means sacrificing some durability, and similarly having high puncture protection usually means added weight and less suppleness.’
Shelley Childs, UK brand manager for Continental, says, ‘Probably the most common mistake I see is people choosing the wrong tyre for their type of riding. Top-end race rubber is designed for exactly that, and not the daily commute.’
There was a consensus among our sources that resolving this comes down to educating riders so they begin to realise more about what the benefits of good tyres are. And it isn’t about spending more money. In fact, sometimes opting for the priciest tyre can make things worse. Taylor says, ‘People will often buy the most expensive and assume that means they must be good, but they could be a completely incorrect choice for their given riding. Online sales are a huge concern in this regard. People don’t take the time to read the technical specification and are just price-driven. A bike shop is a better choice because the staff will usually offer advice that is based on first-hand experience of the tyres they sell, and will speak more frankly to the customer and direct them more effectively to suitable tyres.’
Tread with care
Any British cyclist knows about riding in the rain, and the common belief is that tyres with a pronounced tread pattern will grip better than a slick tread when the tarmac is wet. But the common belief is wrong.
‘The tread pattern on bicycle road tyres is little more than an aesthetic addition,’ Schwalbe’s Taylor says. Morgan Nicol, technical officer for Challenge Tyres, explains, ‘Tread on a tyre is psychological. We put tread on our tyres mainly because the pro teams we supply won’t accept it in their heads that slick treads can be just as grippy and may be faster. No matter how much testing we do to prove it, they want the look of the tread. It’s just what riders are used to.’
‘There may be a tiny amount of water dispersion but the reality is bicycle tyres do not aquaplane,’ says Taylor. ‘The contact area is much smaller than a car and the contact pressure is much higher. The floating effect of aquaplaning could only theoretically be achieved on a bicycle ridden at speeds over 200kmh.’
Childs concurs, saying, ‘Look at the top models from many of the top brands and they are slick. The contours and patterns are mainly cosmetic. We’re driven by the consumer market and OE [original equipment] buyers, and they want the tyres to look visibly attractive too. That’s a powerful sales tool, but it won’t necessarily grip any better.’
So if it’s not the patterns on the tread that are providing grip, what is? Nicol says, ‘It ’s about surface area contact, and that’s governed by the way the tyre deforms, but also what the surface it’s connecting with looks like. Asphalt has a surface texture, and you need the tyre to deform, which happens in two ways: firstly the carcass flexes to allow the tyre to deform and move with the road surface, and secondly the tread material itself deforms.
‘The tread is usually responsible for absorbing the higher frequency vibrations and smaller surface changes, whereas the tyre volume will absorb bigger impacts and deformation caused by bumps or potholes etc. Tyre pressure is obviously a key determinant in this too. You need to strike a balance. Basically [for optimal grip] it’s a question of keeping the tyre on the ground. You don’t want the tyre to bounce. If it’s in the air, even for a tiny fraction of a second, especially during cornering, it’s often this that will cause a slide as the tyre comes back into contact with the surface again. This is even more likely in the wet. It’s the main reason why we use more latex rubber, as it rebounds less aggressively than a vulcanised butyl rubber.’
Childs adds, ‘By absorbing energy rather than rebounding you upwards, the tyre stays in contact with the ground, which improves grip and also helps to reduce the rolling resistance.’
And how do you know if a tyre is supple or not? Generally speaking, the higher the thread count (measured in threads per inch, or TPI), the more supple the tyre will be, and potentially the more grip it should have. But be aware that some companies artificially boost the stated thread count by layering fabric casings of a low TPI on top of one another to claim a high TPI. As Taylor says, ‘This is often misleading as manufacturers do not always quote TPI in a comparable way. So a 360tpi tyre could be three 120tpi layers.’
The dreaded hiss
The puncture gods are easily agitated and will halt you in your tracks if you allow the thought to creep into your mind that it’s been at least six rides since you last had one. As Schwalbe’s Taylor initially alluded to, softer and more supple compounds, while helping with grip and rolling resistance, are also more prone to punctures, which is why tyre manufacturers are often forced to make compromises in design.
‘Softer, more supple treads feel good to ride and offer a lot of grip, but they also pick up more road debris and are less resistant to cuts’
Nicol at Challenge says, ‘There’s no perfect answer for puncture protection versus ride quality. There’s definitely always a trade-off. You need to have a thicker layer of rubber for the tread to prevent objects piercing through so easily, but that directly impacts on the ride quality. Softer, more supple treads feel good to ride and offer a lot of grip, but they also pick up more road debris and are less resistant to cuts.’
Generally, tyres lower down the range use more rubber for thicker treads, so while they may be slightly heavier, their durability and punctureresistance often improves dramatically. ‘They are in the range for a reason,’ says Continental’s Childs, which harks back to his earlier point about choosing according to your needs.
‘Tyres can provide an instant performance return for your investment, unlike power meters and gadgets like that,’ he adds, ‘so do your homework and be honest about how and where you ride, and you will soon narrow down your shortlist from the huge amount of choice.’