After months of rumours, weeks of speculation and almost a week of full public display at the Tour de France, Continental, SwissSide and DT Swiss have finally officially unveiled their much-anticipated aero road tire. Yes, this is a new tire from three different brands, each bringing their own expertise and input to the development, so it’s no surprise that each now wants a piece of the credit.
The result of this three-way development program is a rather unique-looking tire, unlike anything in Continental’s current line of premium road tires, with offset cutouts or knurling or cavities: call them what you will, the trident of brands call them vortex generators. , dotted all around the tread and several brand logos dotted around the sidewall.
It’s not exactly a pretty looking tire, but that’s not the point. Unlike the traditional good-looking and sometimes fast-spinning classic brown-side tires or even the existing regular-looking Conti GP 5000 S TR, the new tire, officially named the Aero 111, is designed with a single function in mind: improved balanced aerodynamics. with low rolling resistance, all in the name of faster driving.
Pull out the other one
Ok, I hear you, “Aero tires…come on,” and you may be right, but the 111 is not aero in that it has a teardrop shape, a pointed tread, or is aero profiled in any other way. In fact, the 111 is shaped no differently than a regular tire. Instead, its aero-enhancing properties come from the 48 vortex-creating cutouts that line both sides of the tread.
The cut-out tread pattern creates a turbulent flow of air across the tire as it rotates, and this induced turbulence is said to aid the flow as it adheres to the rim profile of the wheel. Conti, DT and SwissSide claim the result is reduced drag on the front wheel system, better use of the ‘sail effect’ and even a more stable front wheel, less prone to crosswinds and stormy conditions. Additionally, Trident claims the design provides an aero advantage regardless of rim design or speed.
That’s a lot of action for a simple tire cutout, and it suddenly sheds light on SwissSide CEO JP Ballard’s comments regarding Rule 105 and tire airflow blockage on the Performance Process podcast earlier this year.
As for the rest of the tire, it’s very similar to the existing GP 5000 S TR in both claimed rolling resistances (the 111 is said to offer a slightly lower rolling resistance coefficient [CRR] but more than the GP5000 TT TR) and other features. The rubber is the same as the BlackChili compound used in the existing performance tires. The new tire also features Continental Vectran puncture protection tape and is approved for use in clinch, tubeless and straight sided (hookless) tubeless configurations.
Available in 26mm or 29mm widths, the new tire is front wheel specific, meaning it’s convenient to pair with a different rear tire, and is priced at a whopping $120/€120. In other words, the aerodynamic gains are only available on the front wheel, so buy a regular rear tire focused on reduced rolling resistance.
WT… S
So how did it all come about? According to press materials sent out by the participating brands, the project started with DT Swiss, who, after involving SwissSide in the development of their aero wheels, wanted to develop a tire to optimize the entire Wheel Tire System (WTS).
The pair quickly created a tire design, but needed a “rubber expert” to bring it to life in a tire combining the advances already made in rolling resistance and grip. That’s where Continental stepped in and the result is the Aero 111 tire. The three brands describe it as a turning point in wheel system development and boldly claim that it will never be possible to develop a tire or rim independently again.
At the heart of the aerodynamic claims are 48 offset cutouts dotted all over the tread. These cutouts create vortices as they rotate at the speed of the tire, effectively creating turbulence and directing and holding airflow around the sidewall and onto the rim.
As wild as it sounds, it’s not exactly a new phenomenon, but it’s pretty well understood in aerodynamics.
But does it work? Cyclists typically do not reach high enough speeds to really benefit from flow control, vortex generators, or induced drag. The 111 tire is different though, as the aerodynamics of a fast spinning tire are not only very different to those of a passive frame, helmet or clothing aero, but with so many cutouts on the spinning tread, it makes sense that they can combine for a stronger effect.
It’s important to say that I’m no aerodynamicist and I haven’t tested the new tires yet, but at least that’s how it works in my head.
As you might expect, Conti, DT and SwissSide have tested the new tire and have some lofty claims about its aerodynamic efficiency. The brands showed graphs indicating similar drag numbers when comparing the 26mm Aero 111 and the narrower 25mm GP 5000s TR. The data comparison uses a speed of 30 km/h and measures between +/-5° camber, with a tire mounted on a DT Swiss ARC 1100 Dicut DB 62 wheel. But beyond this +5° camber angle, the Aero 111 equipped bike showed a significant reduction in drag and an even greater benefit below -5/-10°.
We weren’t given the actual numbers, so we have to decipher the best we can from the graphs as to what the actual energy savings are. At higher speed (45 km/h) both tire variants remained much closer and more consistent from roughly -12° to +12° camber, although slightly faster with the Aero 111. Beyond this range, from -15 to +15 outwards, the red line representing the Aero 111’s drag continues to drop, presumably as the bike takes on the so-called sail effect, meanwhile the flow has stopped on the wrapped GP 5000s TR rim. and so is the pull up. The result, according to these graphs, is a frankly amazing 10-15 watts at the outer ranges of yaw deflection…really?
All tests have one common theme: the Aero 111 is either slightly faster or mostly seems to wash other tires at lower camber angles. Lower yaw angles – where anyone overly concerned with aerodynamics usually tends to work at increasing race speed – will reduce the effective yaw angle. So how representative are the higher yaw conditions where the Aero 111 looks significantly faster since they usually only occur 1) when the rider is experiencing significant crosswind conditions or 2) the speed is much lower?
In such scenarios, aero may not be the main concern, but the trident claims otherwise. We often think of aero as going faster, but aero is also about handling in stormy conditions. An aerodynamically poor setup that stalls at higher yaw angles will cause the rider to experience more unpredictable and less controllable handling as the front wheel is battered and bumped. We’ve all experienced that moment when a gust of wind catches the front wheel. Continental claims the 111 Aero’s characteristics mean it allows for more predictable handling with fewer sudden jolts.
The brands had wind tunnel data to demonstrate this as well, with a steering torque test setup to measure the torque exerted on the front wheel across the corner. The marks again showed results that seemed to demonstrate that the 111 performed better at 30 and 45 km/h than the GP 5000s TR, which exhibited a shock-like sudden impact of about +/-10° at lower speed and +/-15° at higher speed .
There has also been testing that suggests the wider 29mm tires have a similar performance benefit on shallower rims and lower speeds of 30km/h.
Finally: testing comparing the Aero 111 with other tires from other manufacturers. Testing focused on a mix of tires, some wider, some narrower, and from brands such as Schwlabe, Pirelli, Enve, Vittoria and Cadex. Unfortunately, again we didn’t get the rough numbers and the other tire lines are so similar in color that it’s almost impossible to tell them apart. Furthermore, the aforementioned GP 5000s TR testing was not overlapped, which would have added a valuable point of comparison. All that said, the graph seems to show that the Aero 111 (red line) is significantly faster on the outer reaches of the yaw, but in reality the two other tires can be a watt faster at a lower angle and speed from -5° to 0 ° and 30 km/h.
The scale changes for a higher speed of 45km/h and the Aero 11 again seems to closely track the other tires from about -12° to +10° or so, but then shows a significant drop in drag, even negative drag. again the sail effect kicks in at the outer yaw distances. Again, I’m not sure if you were going 45km/h and you’d experience a constant -20° yaw, so the difference in aero speeds may be a dampening point, but again, the aero and handling advantages of the Aero 111 seem to be apparent in the graph.
111 we go, we all go
The Aero 111 tire is one of those things that looks ridiculously simple, but in reality probably took a lot of work to refine and create.
We have both the 26mm and 29mm versions to test, but haven’t ridden them yet (they arrived the day before I set off to do the Tour de France).
After holding the new tires I can say that the shoulder or tread to sidewall transition is perfectly smooth, even more so than the GP 5000s TR. The brands didn’t specifically mention this in the presentation of the new tire, but I wonder if it also contributes to the tire’s aerodynamic performance.
There are also plenty of other questions that only driving and testing will answer. Questions like: How does it work in wet weather? It is more or less puncture and cut resistant than the GP 5000s TR which I have had great luck with but have seen others cut and puncture on the first ride?
Then there are questions we may not be able to answer. Questions like: How much of the aerodynamic gain is lost if the cutouts fill up with dirt or just wear out? And what is the wear rate? All brands claim that wear rates are in line with other GP 5000 tires and that tests they have conducted show that aerodynamic gain does not decrease significantly as the tire wears. They’ve also included a three-point wear indicator in the tread to help track wear; probably once you exceed all three the tire is worn out and no longer aero.
Finally, there was one question that SwissSide’s JP Ballard could now answer for me: “Why is it only the front wheel; is there anything we are giving up by going with the Aero 111 and what if someone wants matching front and rear tires? Ballard’s answer was quite simple. “It’s a cost consideration,” he said. All the aerodynamic gains are in the front, so adding a more expensive tire to the rear offers no additional gains. As such the advice was, save the money and run the S TR on the back.
Whatever the answer to these questions, the trident of DT Swiss, Continental and SwissSide may have just created a new segment in the aviation market. Until now, all the development of the aero system of the wheels has been on the wheel itself. Any “aero tires” up until now have mostly been a happy accident or offset by terrible rolling resistance. Aero 111 is the exact opposite of an accident; it was a deliberate effort by several performance companies to make a tire that was aero and fast. As with everything in cycling, if it’s a winner, expect to see countless others follow suit with a whole host of new takes on aero rubber and a whole new aero race.
What do you think of this story?