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Tech feature: The work of Wheel Energy

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Tyres are first warmed up and 'broken in' before rolling resistance measurements are taken.

Tyres are first warmed up and 'broken in' before rolling resistance measurements are taken.
(Image credit: Jonny Irick)
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The 'break-in' station puts a set number of hours on tyres before testing is done.

The 'break-in' station puts a set number of hours on tyres before testing is done.
(Image credit: Jonny Irick)
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Wheel Energy tests tyre rolling resistance using a number of different surfaces.

Wheel Energy tests tyre rolling resistance using a number of different surfaces.
(Image credit: Jonny Irick)
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Test tyres are mounted on control wheels and applied to the rotating drum with hydraulically controlled pressure.

Test tyres are mounted on control wheels and applied to the rotating drum with hydraulically controlled pressure.
(Image credit: Jonny Irick)
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Test conditions are carefully controlled and monitored to yield consistent results.

Test conditions are carefully controlled and monitored to yield consistent results.
(Image credit: Jonny Irick)
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One of Wheel Energy's most important tests covers rolling resistance.

One of Wheel Energy's most important tests covers rolling resistance.
(Image credit: Jonny Irick)
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Tips of various shapes and sizes are used in the puncture tests.

Tips of various shapes and sizes are used in the puncture tests.
(Image credit: Jonny Irick)
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While this test only provides inferential data on sidewall cuts - rather than punctures - Wheel Energy says it is currently developing another test that can simulate the types of tyre failures caused by events such as grazing rocks.

While this test only provides inferential data on sidewall cuts - rather than punctures - Wheel Energy says it is currently developing another test that can simulate the types of tyre failures caused by events such as grazing rocks.
(Image credit: Jonny Irick)
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Wheel Energy directs these test tips into tyre crowns and sidewalls to test puncture resistance.

Wheel Energy directs these test tips into tyre crowns and sidewalls to test puncture resistance.
(Image credit: Jonny Irick)
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Water is applied to the tyres to simulate wet-weather traction.

Water is applied to the tyres to simulate wet-weather traction.
(Image credit: Jonny Irick)
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Wheel Energy tests tyre friction in both upright and angled orientations to simulate straight-line and cornering grip.

Wheel Energy tests tyre friction in both upright and angled orientations to simulate straight-line and cornering grip.
(Image credit: Jonny Irick)
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Wheel Energy keeps a number of real-world samples of road surfaces on hand to provide more useful data.

Wheel Energy keeps a number of real-world samples of road surfaces on hand to provide more useful data.
(Image credit: Jonny Irick)
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Tire friction is tested by controllably moving a small section of road material against a stationary wheel.

Tire friction is tested by controllably moving a small section of road material against a stationary wheel.
(Image credit: Jonny Irick)
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Tires are controllably compressed on the translucent surface and then the contact patch is photographed from below.

Tires are controllably compressed on the translucent surface and then the contact patch is photographed from below.
(Image credit: Jonny Irick)
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The tyre contact patch test station incorporates a hydraulic cylinder to apply a consistent load.

The tyre contact patch test station incorporates a hydraulic cylinder to apply a consistent load.
(Image credit: Jonny Irick)
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Wheel Energy also tests tyres for other vehicle types as well.

Wheel Energy also tests tyres for other vehicle types as well.
(Image credit: Jonny Irick)
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We spotted these Bontrager prototypes treads during our tour of the Wheel Energy facility. By our eye, it appears to be a further evolution of the company's XR3 tread design.

We spotted these Bontrager prototypes treads during our tour of the Wheel Energy facility. By our eye, it appears to be a further evolution of the company's XR3 tread design.
(Image credit: Jonny Irick)
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Slick treads maximize the surface contact area of road tyres on the pavement in theory but in reality, asphalt is far from a perfect surface and tread designs can offer additional mechanical adhesion in certain situations.

Slick treads maximize the surface contact area of road tyres on the pavement in theory but in reality, asphalt is far from a perfect surface and tread designs can offer additional mechanical adhesion in certain situations.
(Image credit: Jonny Irick)

Tucked inside a small industrial complex in Nastola, Finland, is the nondescript grey building of independent third-party tyre testing facility Wheel Energy.

Using a battery of custom purpose-built machines, founders Petri Hankiola, Veijo Pulkkanen, and Marko Savolainen are addressing some of the common questions surrounding bicycle tyres and they're coming up with some interesting answers that no longer have to rely on word of mouth, tradition, or intuition for their veracity.

Take these conclusions for example:

Wider tyres roll faster than narrower ones: Many riders have argued for years that narrower tyres – especially on the road – are faster and more efficient than wider ones when in fact, the opposite is true. According to Wheel Energy, the key to reducing rolling resistance is minimising the energy lost to casing deformation, not minimising how much tread is in contact with the ground.

All other factors being equal, wider casings exhibit less casing 'bulge' as a percentage of their cross-section and also have a shorter section of deflected sidewall. How big a difference are we talking about here? For an equivalent make and model of tyre, Wheel Energy claims the 25mm-wide size will measure five percent lower rolling resistance on average – the supposed average limit of human detection – than the more common 23mm-wide one.

Unless you're a pure climber and solely focused on weight, the takeaway message here is that you'll go generally faster on wider rubber even if it's slightly heavier.

Larger diameter wheels roll faster than smaller ones: Yep, 'tis now been confirmed in the lab – 29ers roll faster than 26ers. Wheel Energy says the effect here is similar to that of tyre width in that larger-diameter tyres exhibit less casing deflection and thus, less energy loss.

In the case of 29ers, there's the additional factor of 29er's lower angle of attack for anything other than a perfectly smooth ground surface. The longer effective lever requires less energy to overcome whatever tyre bulge exists at the contact patch so more forward momentum is maintained.

In addition, Wheel Energy's analyses of tyre contact patch have confirmed that 29" tyres don't have a bigger footprint than otherwise identical 26" ones. While the total area is the same, the shape of the patch is longer and narrower on 29ers, though.

Higher thread counts aren't always better: According to Wheel Energy, higher thread count casings are generally lighter and suppler than tyres with lower thread counts since they absorb less rubber during the vulcanisation process (non-vulcanised tyres such as most high-end tubulars exhibit their own characteristics).

However, they also suffer from decreased puncture resistance since the individual cords are thinner and easier to cut. Interestingly, Wheel Energy claims medium-count casings (around 60tpi) may offer the best all-around performance for everyday use. As compared to 120tpi casings, they can actually roll faster and are much more resistant to cuts while often carrying just a slight weight penalty.

If cut resistance is highest of your list of priorities, 30tpi tyres are apparently the way to go but you can also expect them to be heavy and slow rolling.

Puncture-resistant belts work but they're not created equal: Nylon, aramid, and other belts placed under the tread do help ward off flats but there are benefits and trade-offs to the various materials.

Tougher ones like aramid are durable and highly cut- and puncture-resistant but their stiff nature also sucks up a lot of energy, thus contributing to rolling resistance. More flexible ones like nylon aren't as bulletproof but offer a better compromise if you still want to retain good performance.

Tread pattern matters, even on the road: The importance of tread pattern is no surprise to the off-road world but common wisdom often says it's a non-factor on pavement where slick treads presumably would deliver the greatest surface contact with the ground and thus, the best grip. However, asphalt is far from a perfect – or even consistent – material. In those cases, certain tread designs can provide some measureable mechanical adhesion with the ground.

Inner tubes matter: Think there's no point in that expensive lightweight tube? Think again if you're trying to go faster. According to Wheel Energy's data, latex tubes roll ten percent faster than common 0.6mm-thick butyl tubes though today's ultra-thin butyl models come admirably close. Just in case you're wondering, the claimed limit of human detection for rolling resistance is about five percent.

How they do it

Wheel Energy's constantly evolving collection of testing machines are no miracles of design innovation or elegance but the fact that they exist at all is noteworthy in that as far as we're aware, it's the only independent test facility of its type in the world.

Currently, there are dedicated stations for rolling resistance, crown and sidewall puncture resistance, friction, and contact patch characterisation with additional apparatuses being designed and built as necessary. Each machine is fully custom-designed, built with computer-controlled hydraulic loading and fitted with industrial load cells for precise and accurate measurements.

Rolling resistance tests are conducted on large-diameter drums with various types of surface treatments, friction tests are done with a wide range of ground types (asphalt, concrete, etc.), and puncture tests can be performed using interchangeable tip sizes and radii. Conditions are kept constant throughout to foster repeatability.

(Photo: James Huang/Future Publishing)