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Are wider road tyres better? What are the advantage of bigger tyres and why should you upgrade?

Monday, September 21st, 2020 3:10pm
Category: Latest News

In the beginning, when roads were nothing more than gravel, early road bikes had fat balloon tyres. As road surfaces improved and bike technology advanced, road bike tyres got narrower. But as roads are deteriorating in quality many road cyclists are once again moving to wider tyres to provide increased comfort and control and the latest advances show improvements in rolling resistance.

Wider tyres are not only plush but fast too. Time to swap out your skinny tyres for fat tyres then?

There have been many technology fuelled trends in the road bike market in recent years but the most interesting and appealing is the popularity of wide tyres. Many new road bikes are increasingly being designed to accommodate wide tyres, tyre and wheel manufacturers are responding with new and improved products, and road cyclists are realising the benefits outweigh any negatives.

Go back 10 years and the 23mm tyre fitted to a narrow rim and inflated to 120 psi was the norm. Today it’s not uncommon to ride a 30mm tyre on a wide rim at 55psi on a modern road bike. Part of the reason for this change is the worsening state of roads; potholes and rough roads are far more common. But it’s the realisation amongst cyclists that wider tyres can improve the road cycling experience.

How can wider tyres improve your road ride?

How so? It’s now understood that wider tyres are actually faster than narrow tyres. This might seem counterintuitive – surely a narrow tyre has to be faster right? – but it’s due to the contact patch and tyre casing deflection.

Let’s look at the contact patch first. A narrow tyre has a long thin contact patch while a wide tyre has a short wide contact patch. The size of the contact patch is roughly the same but it’s a different size that is critical.

That short wide contact patch of the fatter tyre results in less tyre casing deflection as the tyre rolls along the road. A tyre deforms when it’s pushed against the road surface by the weight of the rider and bike, and with a shorter contact patch the tyre is deformed along less of its length than the longer contact patch. This reduced casing flex means less hysteresis loss (energy lost through heat).

It’s also because the wider tyre is able to absorb imperfections in the road so energy normally lost moving the bike and rider up and over a bump with a narrow tyre is conserved, resulting in a lower rolling resistance You travel faster for the same effort.

Simply put, tyres are the main suspension on your bicycle and just the same way you wouldn’t drive a car without suspension – it would be harsh and slow on normal roads – the more reason there is to see the benefits of wider tyres providing comfort and speed on regular roads.

This can also result in a more comfortable ride because you’re not having to absorb the impacts and vibrations through your arms and legs, which can lead to fatigue on very rough roads or long-distance rides.

With a wider tyre acting like suspension you’ll enjoy a smoother ride and be less tired from literally being shaken about when riding a narrow high-pressure tyre on rough roads. So more energy for pushing on the pedals.

Don’t just take our word for it. Highly regarded Tour Magazine conducted a thorough test examining and testing lots of tyres and concluded that a wider tyre was faster than a narrow tyre. You can see all the results of that in-depth test here .In another test by Cyclist Magazine, a 25mm tubeless tyre at 95-100psi was found to provide the same rolling resistance as a 30mm tubeless tyre at 72-80psi. And you know that the wider tyre is going to offer a smoother ride on rough roads.

How to get the best performance from a wider road tyre

Key to getting this performance out of a wider tyre is lower pressure. Ride a wide tyre at the same high pressure as a narrow tyre and the ride will be hard and horrible. To get the best out of wider tyres you have to lower the pressure to get the biggest benefit.

In our experience, 60-75psi is a good starting point on a 28mm wide tyre. That’s much lower than the 120 psi common a few years ago. So be sure to experiment with lower pressures than you are used to and try one of the many free apps available that let you punch in your weight and tyre size and get a recommended pressure. Wider tyres do offer more opportunity to choose the way the tyre feels by going higher or lower compared to a narrow tyre which needs to be inflated higher.

Upgrading to wider tyres, therefore, is an easy way to inject more comfort into your road bike if you’re regularly finding your current narrow tyres are rough and harsh on your local roads – unless you reside in Mallorca where the roads are glass smooth! Key to unlocking this extra comfort and performance then is fitting the widest tyres your bicycle frame and fork will accept, so check carefully with the manufacturer to see how wide you can go. Many bicycle companies err on the side of caution when advertising max tyre clearance and sometimes it’s possible to go wider.

What about rim width…?

Another factor to consider is rim width. Wider tyres offer many benefits but a wide tyre on a narrow rim can introduce previously unforeseen disadvantages. A wider tyre presents more frontal surface area than a narrow tyre. Previously a road rim would feature a 17mm internal rim width but we’re now seeing up to 23 and even 25mm internal rim widths being developed specifically for wide tyres.

A wider rim provides improved aerodynamics when combined with a wide tyre, ensuring a smooth profile and also lends more stability and control to bike handling as the wide tyre is less likely to squirm on the wide rim. A wide tyre on a narrow rim results in a lightbulb profile, but fit the same wide tyre to a wide rim and you have U-shaped profile that gives the tyre more support at lower pressures. For this reason, modern wheel rims are growing in width to meet this surge in the popularity of wide tyres.

The gravel-influence

Road cyclists are also going to wider tyres for another reason: gravel. The massive popularity of gravel, adventure and bikepacking has opened up many cyclists to the wonders of riding a drop bar bicycle off-road in the woods and across open countryside. It gets you away from congested roads and angry motorists, lets you explore more than just the vast road network – you’ll be surprised just how much countryside is accessible via bridleways and byways – and is incredibly rewarding and liberating.

Best of all, you can ride many smoother gravel and dirt roads on a fat road tyre – this author was regularly riding a steel road bike with 23mm tyres down rocky tracks in his youth. It’s even possible to convert a road bike into a light gravel bike with just a change to the widest tyres you can fit.

How wide should you go?

So how wide should you go? Is the widest better? That depends on many things, but namely what your road bike will take. But is there a benefit in going even wider? At the moment the sweet spot for many road cyclists and current road bikes designs is 28 to 32mm. One negative to wider tyres is both the increased weight and extra aerodynamic drag the wider tyre produces. Both factors can be mitigated to some degree by modern lightweight disc-brake wheelsets and wider rims designed around wide tyres.

If outright speed is not your focus, and you’re not racing, the benefits of wider tyres increase offering more comfort and traction than previously available. Rolling resistance is a bigger factor at speeds below 25kph where arguably many normal cyclists spend a lot of time cycling, and the benefits of a wider tyre can be realised to the full. At road racing speeds aerodynamics is the biggest force to overcome with rolling resistance making up much less of the equation.

For all but the most diehard racing cyclists then – and even then many pros are switching to wider tyres than ever before – the benefits of wide tyres arguably outweigh any negatives. They provide lower rolling resistance, more comfort on rough roads and better traction and control in a wider range of conditions, which all mitigate the small weight penalty of the extra rubber.

For many cyclists, tyre width is becoming a key factor when choosing their next road bike and with even aero race bikes now being able to take 30mm tyres and endurance bikes moving up to 38mm in some cases, there’s never been a better time to reap the benefits of wider tyres.

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