Trek's Bontrager brand has expanded its Aeolus range with its "fastest wheels ever", the outgoing XXX models replaced by RSL51, 62 and 75 wheels. The Aeolus Pro 51 is also added, taking the same rim shape as the RSL model and sporting a slightly friendlier price. It’s tubeless clinchers only now for the pro riders.
While we didn’t spot them at the time, fans of pro road racing have likely already seen the new Bontrager Aeolus RSL wheels. Former World Champion Mads Pedersen rode them at Paris-Nice and Jasper Stuyven won Milan-San Remo while using the RSL75 rear wheel.
The new wheels add to the Aeolus RSL 37 model that we saw with the launch of the 2021 Trek Emonda last year.
Bontrager says that instead of starting the design process with a tyre size in mind as is usually the case, it began designing the new Aeolus RSL wheels with a clean slate. This, Bontrager claims, allowed it to design the fastest system – wheel and tyre.
Part of the redesigned process was a switch from 2D to 3D CFD (computational fluid dynamics) in their iterative feedback loop that Bontrager says allowed them to incorporate more variables that affect speed. This, they claim, allowed the engineers to “better replicate real-world conditions and make wheels that aren’t just faster but represent a step-change in speed.”
This testing, Bontrager claims, showed that “the wider 23mm inner width is proven to roll with less drag, provide better aerodynamic connection with tyres and add to the overall speed gains. Plus, it lets you run lower tyre pressures for a smoother, less fatiguing ride.”
During Bontrager’s presentation, they were very keen to show us how the new wheels stack up against the Aeolus XXX range when measured in the same aero and stability tests. They popped the results on the same axis used for the Aeolus XXX wheels and the Aeolus RSL wheels didn’t fit.
Essentially what the graph shows and what Bontrager is claiming is that the new wheels are both faster and more stable in crosswinds than the Aeolus XXX wheels and once Bontrager put the old and new wheels on a graph with a big enough axis, the results suggested that the Aeolus RSL 62 was the equivalent of 6.5 watts faster than the Aeolus XXX6 wheelset while also being around 7g/degree more stable in the wind.
The very faint writing at the base of the first graph makes for some interesting reading. The test data is an average from tests over 0-20º yaw. The Aeolus XXX wheels in the test were rim brake wheels while the Aeolus RSL range is a disc-only platform.
It is easy for brands to drown us all in data, but Bontrager has put some of the data into real-world applications featuring their pro riders.
Say, for example, that Trek-Segafredo’s Mads Pedersen finds himself in a sprint finish at the Tour de France. Here, Bontrager says, the Dane will lay down 1,500 watts and for that effort, should he opt for the new RSL 62 TLR over the old XXX 6 tubular wheels, he’d save the equivalent of 34 watts.
At the front of the peloton, when doing the donkey work during the majority of the stage, Bontrager says that the RSL 51 TLR saves the equivalent of 6.3 watts over the XXX 4 tubular wheels.
The main part of the wheel, and the most interesting to us, is the new rim. Unfortunately, this is the part that Bontrager is most vague about. All that they will say is that the tubeless-ready RSL wheels get RSL-level OCLV carbon which, they claim, is “the lightest and strongest available.”
While the construction of the rim is a little unclear, the straight-pull hubs feature DT Swiss 240 Ratchet EXP internals with 36T ratchet rings. This was a system that was launched last year with the main feature being that the driveside hub bearing in the rear wheel had been moved outboard and into the inner ratchet ring. Exciting stuff, we know, but this, DT Swiss claimed, increased axle stiffness by 15%.
Bontrager again turns to DT Swiss for the spokes with all RSL-level wheels getting 24 DT Swiss Aerolite spokes in the front and rear wheels. DT Swiss ProLock nipples pull everything together.
The hubs are made for centre-lock rotors and come set up for 12mm thru-axles, though conversions for QR and 15mm axles are available.
In the box, you get a tubeless rim strip, a tubeless valve and also a traditional rim strip for use with tube-type clincher setups.
Aeolus Pro 51 - Front/Rear - £549.99/£649.99
Aeolus RSL 51 - Front/Rear - £899.99/£1099.99
Aeolus RSL 62 - Front/Rear - £899.99/£1099.99
Aeolus RSL 75 - Front/Rear - £899.99/£1099.99
We've asked very nicely for a set of the new wheels so look for a review on the site soon.