Bontrager’s new Aeolus RSL and Pro wheels promise more speed and comfort. Bontrager aim to achieve this through a wider rim, which is claimed to form a more aerodynamic unit with the tire while also allowing lower tire pressures for improved comfort. We’ve got all the details.
With the Aeolus RSL and Pro wheels, Bontrager introduce the latest members of the Aeolus range. However, they’re not just any new wheels: Bontrager believe they’re the fastest wheels they’ve ever made. They’re also claimed to be lightweight and little affected by crosswinds. The world tour professionals of the Trek-Segafredo team led by former world champions Mads Pedersen and Jasper Stuyven already put the new wheels through their paces and tested these claims. Pedersen rode on them at Paris–Nice and Stuyven even took the top step at Milan–San Remo on them. Talk about a baptism of fire. What variants are there, what benefits do they have to offer, and what technology do they rely on? We’ve got the answers to each of these questions.
The new variants of the Aeolus range
At the top of the range, the new wheels include three RSL models. The only difference is in the rim profile, whereas they all feature the same technology: OCLV RSL carbon, DT Swiss 240 hubs with Ratchet EXP 36 freewheels, DT Swiss DT Aerolite spokes and DT Swiss Pro Lock nipples. Bontrager have also introduced a new, slightly trimmed-down and more affordable Pro model with a 51 mm profile. What differentiates it from its more expensive counterparts is the somewhat heavier OCLV Pro grade carbon and DT Swiss 350 hubs.
All four RSL and Pro models are exclusively available as tubeless-ready, clincher, disc brakes versions with an impressive internal width of 23 mm and built with 24 spokes front and rear. You get an 11-speed freewheel as standard, the wheels rotate around 12 mm thru axles, and the brake rotors rely on the Centerlock mounting system. Adapters for 15 mm thru axles and quick releases are available separately, as are 12-speed freewheels. The scope of delivery includes tubeless valves, tubeless rim tape and a conventional rim tape. We’ve listed the details of each model in the table below.
|Profile depth||Hub||Weight (Set)||Price|
|Aeolus Pro 51||51 mm||DT Swiss 350||1,590 g||€ 1,300|
|Aeolus RSL 51||51 mm||DT Swiss 240||1,410 g||€ 2,400|
|Aeolus RSL 62||62 mm||DT Swiss 240||1,520 g||€ 2,400|
|Aeolus RSL 75||75 mm||DT Swiss 240||1,645 g||€ 2,400|
The technology behind the brand new carbon wheels
To make them as fast as possible, Bontrager have taken on the two major braking forces acting on the wheels: wind resistance and rolling resistance, aiming to minimise both. To do so, Bontrager optimised their development process, relying on software-based 3D simulation. According to the American brand, the system evaluated countless rim profiles over several months while viewing the wheel as a whole with the tire fitted, learning new things with every run. Moreover, prototype models were taken on test rides during which wind sensors recorded the wind’s angle of attack while the test riders noted situations in which the wheels felt unstable, feeding this additional information into the 3D simulation. The aim of this process was to develop a rim profile that not only reduces wind and rolling resistance but also remains stable in crosswinds. Bontrager’s findings: a rim with a 23 mm internal and 30 mm external width combined with a 25 mm tire achieves the best results in terms of wind and rolling resistance. 28 mm tires are also an option and though they aren’t as aerodynamic, they might have less rolling resistance. Wheels of this width can be ridden at lower pressures and thus provide increased comfort. Mads Pedersen rides his Aeolus RSL wheels with Pirelli tubeless clinchers pumped to 6 bar at the front and 6.2 bar at the rear.
What does it all translate to in the real world?
Enough of the theory. Do you need the Aeolus RSL wheels to win the most important battles, i.e. the home-straight sprints against your riding buddies? Here’s the deal: according to Bontrager, the Aeolus RSL 62 wheels save you an average of 30.6 W in wind resistance and 3.3 W in rolling resistance compared to Bontrager XXX 6 tubular wheels with a rider output of 1,500 W. The 33.9 W saved can be converted into additional propulsion, giving you an advantage of 1.6 m in a typical sprint finish, according to the manufacturer’s mathematics. That can make all the difference when sprinting towards the finish line. If you’re not into sprinting, you might be more interested in the claim that the Aeolus RSL 51 wheels require an average of 2% less power than Bontrager XXX 4 tubular wheels to maintain a constant speed. Okay, enough of that. We know that these numbers were calculated without considering real-world variables. Aerodynamic drag also always includes the rider, generating around 75% of the total. If you leave your jersey fluttering in the wind or you can’t hold an aerodynamic position for long enough, these advantages can quickly lose relevance. Besides, not everyone can put out 1,500 W. So, do the Bontrager Aeolus RSL wheels have fewer advantages for the average rider than for the pros from Trek-Segafredo? No! However, the advantages aren’t the same. While the professionals have to fight for every second on the clock, hobby riders like us can benefit psychologically, knowing that we’ve got the best equipment available on the market and not wasting any effort. That said, the main advantage is the increased internal rim width. Increasing the rim width increases the volume of the tires, allowing them to generate more comfort. In turn, more comfort means less fatigue and more reserves for demanding situations.
What is the take-away from these new wheels?
The findings from the new Aeolus RSL and Pro are multifaceted and confirm current trends. The first thing you notice is the trend towards wider wheel-tire systems. DT Swiss have been relying on a 20 mm internal width for the ARC 1100 series for a while already, the Roval Rapide CLX and Alpinist CLX wheels feature a 21 mm internal width, ENVE offer various 21 mm models, and now Bontrager have upped the bar to 23 mm. According to the manufacturer, the wider design reduces wind and rolling resistance. The possibility of riding with lower tire pressures and thus having more comfort is a positive development and especially beneficial for non-professionals. Performance and comfort will continue to go hand in hand ever more in the future. The second insight is that clinchers are increasingly making their way onto the professional circuit. While the majority of pro-peloton riders are still on tubular tires, the riders of Trek-Segafredo, Deceuninck-Quick-Step and Bora-Hansgrohe no longer have a choice – at least officially: the latest wheels from components brands Bontrager and Roval are exclusively compatible with clinchers. The victory of Kasper Asgreen (Deceuninck-Quick-Step) at the Tour of Flanders shows that this development certainly isn’t slowing them down. By doing so, the manufacturers don’t have to develop a clincher version for the mass market while also developing a tubular version for a handful of professionals and enthusiasts. Tubular tires seem to be nearing their end for professionals too, and while the Roval Rapide CLX and Alpinist CLX still require a tube, the Bontrager Aeolus RSL and Pro are paving the way for tubeless. The final insight is that brands are starting to focus more on customer loyalty. Bontrager’s Carbon Care program offers a lifetime guarantee on their carbon wheels and free replacement for wheels that are damaged within the first two years. DT Swiss and Roval provide similar guarantees. We find this an encouraging development that can make purchasing expensive carbon wheels a lot more attractive to non-sponsored athletes.
With the Aeolus RSL, Bontrager claim to have launched their fastest wheels yet. Their watt and speed calculations seem to confirm this thesis and might make all the difference for the pros. However, hobbyists are more likely to appreciate the increased rim width and possible comfort gains. For now, it remains to be seen how the wheels perform in our real-world tests.
For more information, visit trekbikes.com
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Words: Tobias Hörsch Photos: Bontrager