Tyre tester

[AndreZA]

Taking the mystery out of tyre testing and development

 

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.

 

Why it matters

Tyre development can be a notoriously black art and with development cycles reportedly taking around a full calendar year for a single model, it's easy to lose an entyre model year if something goes awry. And once a mould is cut, it's more or less a done deal whether or not the tyre is actually any good.

 

As such, companies such as Specialized, Trek, and Vittoria (and whoever else is willing to pay) now commission Wheel Energy to provide valuable data to aid the process.

 

Specialized is especially open in how Wheel Energy's information has improved its range – and exposed the flaws. By Specialized's own admission, the company had been falling behind in recent years in the tyre market – where, ironically enough, it first got its start in the industry back in the late seventies.

 

In particular, it even says its previous-generation S-Works Turbo road flagship was a whopping 25 percent slower than most of its competition... Ouch.

 

That's supposedly all changed now. Thanks to data from Wheel Energy, Specialized tyre product manager Wolf vorm Walde claims the new model is now on-par with the rest of the high-end road tyre market in terms of rolling resistance.

 

Among the changes are reduced rubber around the shoulder of the tread and reduced rubber thickness in the casing, both of which help minimise the amount of energy lost in casing deformation as the tyre rolls down the road.

 

In the case of Specialized's revamped Roubaix clinchers, it was also found that sidewall puncture resistance could be improved without hampering rolling resistance by simply increasing the casing ply overlap in that area.

 

Based on our initial test rides on a pair of pre-production samples, we'd say that data has been put to good use as they feel notably lively for tyres that aren't necessarily intended for racing – and perhaps even better than Specialized's previous-generation Turbos though we still need to put more testing time in before drawing any firm conclusions.

 

If other Wheel Energy clients can make similar improvements in efficiency both in terms of tyre development and performance then ultimately we all stand to gain in terms of the quality of tyres on the market as well as the pace at which they improve – not bad for a little nondescript grey building in the middle of the woods in Finland.

 

http://www.cyclingnews.com/features/tech-feature-the-work-of-wheel-energy

.

[Velouria]

So wider, bigger, tyres with low thread counts and latex tubes are the way to go?

 

Does this mean we can finally end all 26" vs 29" threads on The Hub?

[Wyatt Earp]

So wider, bigger, tyres with low thread counts and latex tubes are the way to go?

 

Does this mean we can finally end all 26" vs 29" threads on The Hub?

Perhaps us taller and bigger guys like you and I could get quicker

[LeTurbo]

Will knobblies fit on my road bike? Could start a whole new fashion.

[stratus5]

Can you actually buy a 25C tire and latex tubes locally?

[MTB_Roadie]

I disagree with the wider tire one.....

 

When my dad used to race, it was proven a narrower tire is faster on acceleration, however the wider tire corners better....

[eggsovereasywithteandtoast]

Theres no right or wrong answer. They themselves, work in a nondescript grey building.

 

Nowhere in the article is the operating temperature(s) mentioned. This variable is suggested to be significant enough, that in its oversight, we propose the

disqualification of this "report" based on poor scientific content.

[eggsovereasywithteandtoast]

... , thought it was a job offer

[Woofie]

Interesting stuff man.

Always known that the wider tire rolls a bit easier than the thinner one.

But to the extent of them saying rather go for the wider one, now that is awesome.

You know how much nicer of a ride you will actually get from a 25c compared to a 23c.

It will be softer, grip better and use less energy. Yes maybe 30grams more, but you still saving.

 

I was TOTALLY taken aback though on the difference of latex tubes.

I use just the cheapest stuff off the shelf.

The lightweight butel tubes are less than half the weight of the bricks I have in my tyres.

But a 10% difference, that is amazing!

Wouldnt go with latex tubes as you need to pump them everyday. And also if you get a puncture they apparantly normally go BANG and you are on the rim in a sec. Not nice at all.

 

BUT the totally awesome news and wow I am so happy now. I am waiting for my tubeless atoms to arrive.

So with having no tubes at all, I just cant wait to feel the way that they are going to roll.

 

SWEET, SWEET, SWEEEEEEEET

[flymango]

How they do it

Wheel Energy's constantly evolving collection of testing machines are no miracles ...

 

Ha!! Just the proof I needed that evolution exists.

[Just Keep Pedaling]

"When my dad used to race, it was proven a narrower tire is faster on acceleration, however the wider tire corners better.... "

 

How was it proven? By careful use of machines and measuring like above or by getting 'seat of the pants' opinions from riders?

[MTB_Roadie]

"When my dad used to race, it was proven a narrower tire is faster on acceleration, however the wider tire corners better.... "

 

How was it proven? By careful use of machines and measuring like above or by getting 'seat of the pants' opinions from riders?

 

You do a few drag runs, acceleration with the narrower tire was faster however the wider tire gives more traction....was with the same car I dont mean proven by all this scientifical stuff....just saying that a narrower tire was faster with the acceleration times.....

Edited February 2, 2011 by MTB_Roadie

[Just Keep Pedaling]

" acceleration with the narrower tire was faster however the wider tire gives more traction....was with the same car I dont mean proven by all this scientifical stuff....just saying that a narrower tire was faster with the acceleration times..... "

 

This makes sense to me as accelation is quite weight dependant (formula 1 car is slower off the mark than a superbike) but continous rolling is more related to power vs. general friction (tyres on road and wind resistance) - where the F1 car now outperforms the superbike).

[Goodbadugly]

Articles like the above are always interesting to read. Let me just put one thing straight before you guys try to flame me. I am not against testing or science. That is a good thing. Especially a meta-analysis. The problem comes when people try to press results of tests into their way of thinking. Unfortunately I have turned into Mr Super Cynic in the last few years due to the bombardment by the media and marketeers.

Lets take the 29er thinghy. We now have "conclusive" evidence that a 29er is faster than a 26er.

BUT I would like to take myself as an example. What makes me slow?

Number one is toting a total mass (bike and rider plus water bottles) 90kg up hill. That is a simple physics law. For the same money I will get a 29er that weighs 1 kg more. So 91kg. This simple uphill will now require me to to work 1% harder.

Another major factor is wind resistance. And don't forget my peddling inefficacy when I am tired.

The really small things that makes me slow are the normal(not ceramic) bearings, my unshaved legs etc. Oh yes, I nearly forgot about the rolling resistance and the smooth rolling effect of my chosen wheel/tire over small obstacles.

This last factor contributes to (lets give it an REALLY high value) 5% of the stuff that slows me down. If I understand correctly, this fatter and bigger tire will roll 5% easier. That is 5% of 5% equals 0.25%. Hmmmm... Wow. Conclusive evidence that I will be 0.25% faster on a flattish road. My Barberton 75km will now be 40 seconds less. So 4 hours 11 mins and 13 secs instead of 53 secs. If you discount the climbs.

Interesting reading though.

Maybe I will join this 29er marketing hype when it is time for a new bike. But first I must train harder and shed 5 kg's and I am rather sure that will make me faster.

[Johan Bornman]

You do a few drag runs, acceleration with the narrower tire was faster however the wider tire gives more traction....was with the same car I dont mean proven by all this scientifical stuff....just saying that a narrower tire was faster with the acceleration times.....

Answer the question. How was this measured? Can you perhaps provide some data?

[Johan Bornman]

The lightweight butel tubes are less than half the weight of the bricks I have in my tyres.

But a 10% difference, that is amazing!

Wouldnt go with latex tubes as you need to pump them everyday. And also if you get a puncture they apparantly normally go BANG and you are on the rim in a sec. Not nice at all.

 

 

Read the label on your cooldrink very carefully. It says, No Added Sugar. Two lines further it will tell you the total sugar content is X percent.

 

The 10% that knocked your socks off is 10% of the tube's contribution to the total drag of the wheel.

 

Considering that an average road wheel loaded to 50kgs creates something like 12 grams* of drag, a 10% saving of the 10% ontribution of the tube to that drag, is 0.12%.

 

Butyl tubes are still the best overall tube. This same study doesn't mention that a latex tube requirs a pomp more often than a stud buck in a cage full of does.

 

 

 

* Thumbsuck from distant memory. It is very, very low though.

Edited February 3, 2011 by Johan Bornman