Conti Aero 111 in the TOUR test: New aero tyre makes its debut at the Tour de France
Robert Kühnen
· 03.07.2024
Mavic was the first manufacturer to consider wheels and tyres as a system and to keep aerodynamics in mind. This was actually logical, as the tyres ultimately form the critical front of the joint aero profile of tyre and rim. The fact that the Mavic system was not a great success was due to the tyre. It was not on a par with top products. Aerodynamics professional Jean-Paul Ballard, head of Swissside and responsible for the aero development of DT products among other things, also had the topic of aero tyres on his radar early on. But it took time to realise the product. "An aero tyre must of course also be top in every other category," says Ballard, otherwise it wouldn't make sense.
Conti Aero 111: Vortex generators like a golf ball
Eventually, a trio of Continental, DT-Swiss and Swissside came together and the expertise from the rubber kitchen, wheel production and aero development was thrown together. The basis of the resulting Aero 111 tyre is Conti's 5000 STR, known as an absolute top tyre, popular with professionals and the rolling reference in TOUR tests. "111" takes up the prototype designation at Conti and stands for the interaction of the three partners. The rubber compound, carcass and construction of the aero tyre are said to be identical to the 5000 STR, only the tread is different. The block-like indentations serve as vortex generators. This is a well-known principle in aerodynamics. The dimples in the golf ball have the same background, as does the fine rib fabric on the upper arms of the time trial suits. "The difficulty lay in designing the profile in such a way that it works for a wide range of wheels and speeds," explains Ballard.
We were able to subject the tyre to an extensive wind tunnel test - on six wheels, from the small aero profile with a depth of 30 mm (DT AR 1600) to full-blown aero profiles with a height of 60 mm, including our Zipp 404 reference wheel and the ultra-wide Roval CX Team (35 mm outer width). Deviating from our normal procedure, we took the measurements on the naked front wheel. The tyre is also intended exclusively as a front wheel tyre because it only has an aerodynamic effect there. We carried out the aero tests with 26 and 29er tyres at three speeds: 30, 37.5 and 45 km/h.
The aero profile prevails in all measurements
In all measurements, the aero tyre outperforms the normal 5000 tyre. The aero tread delays or prevents the flow from separating from the wheel when the tyre is slanted. With some rims, the front wheel is even propelled when the aero tyre is fitted. The greatest qualitative differences occur at low speeds (where diagonal flow is also more likely). Naturally, more power can be saved at higher speeds; on average, the front tyre saves 1 to 2.5 watts. In some cases, however, ten watts or more can be saved if the airflow is particularly oblique. The tyre therefore offers advantages not only to fast riders, but to all road cyclists who need speed. The aero effect also improves handling: in tests on the road with Zipp 404 wheels, it was noticeable that the aero tyre smoothed the ride. Larger steering deflections due to gusts were less frequent than with the standard tyres. This corresponds with the steering torque measurement in the wind tunnel, which shows smoother curves.
The tyre has already been spotted on Decathlon AG2R La Mondiale bikes at the Tour de France. Tadej Pogacar is also a potential beneficiary. What do the pros get out of the aero tyre?
On the one hand, they benefit from better handling in conjunction with deep rims, as stalling occurs less frequently and the front wheel rides more smoothly through gusts. On the other hand, aero performance improves significantly when a crosswind blows on an incline, as even professionals experience stronger diagonal flow.
Time trial or aero tyres? Spoilt for choice
And what about the time trial? Are the tyres an advantage at all at the extreme time trial speeds of the pros, when the qualities are particularly effective at lower speeds? In time trials, it's a trade-off between the slightly better rolling of the thinner rubberised time trial version of the tyre, the Conti STR TT, and the aerodynamic qualities of the Aero 111, which has the normal rubber thickness of the Conti 5000 STR. We are pretty sure that the Aero 111 will therefore be the front tyre of choice for the final time trial in Nice, because there is a lot of climbing as well as rapid descending. This is where the tyre can show off its two qualities. The time trial tyre without the aero tread will be used on the rear wheel.
Performance-orientated leisure riders will find the Aero 111 a means of making their aero wheels faster and more controllable in many situations. We were able to test the smooth riding behaviour of the Aero 111 on the descent from the Stilfser Joch during the Dreiländergiro. The tyre is tubeless and hookless compatible and is available in 26 and 29 mm widths for 119.95 euros. The 26 mm version weighs 248 g, the 29 mm counterpart 280 g. The tyre was easy to fit and sealed immediately in the tubeless set-up.
Conclusion on the Conti Aero 111
The Conti Aero 111 tyre is a stunner and an example of how the art of engineering can push the boundaries further and further. What is particularly impressive is that the tyre works under a wide range of conditions and shows aero effect even at low speeds.
