Fresh off of the thrill of the classics, the Bontrager wheel team announces a counterpart to its lightest ever Bontrager Aeolus RSL 37 wheels. The new wheel line, better yet – let’s call it an expansion pack – offers the same hub and attention to detail as the Bontrager RSL 37 wheels and is available in three new depths. The expanded offering drills deep into rim aerodynamics, saving precious watts, and even includes a deeper option for the more affordable Pro line.
What’s new for the Bontrager Aeolus line?
Bontrager’s Aeolus RSL line effectively replaces the Aeolus XXX line of wheels. This disc-specific, tubeless wheel line covers a fast array of conditions and terrain. The expanded line up adds the new 51, 62, and 75mm deep profiles to give the RSL family four optons.
The real story of the Bontrager Aeolus line is the updated rim depth, shape, and width. For this wheel, they moved to a slightly wider 23mm inner (over the 21mm inner on the Aeolus RSL 37 model) and a 31mm outer.
Bontrager came to the conclusion that many wheel companies have; having a wider rim width (within reason) is proven to roll with less drag and provide a better aerodynamic connection with the tire. In testing, they found that the 23mm inner width matched with a 25mm tire yielded the fastest set up.
Only, in our testing that 25mm tire actually measures over 28mm when set up tubeless. And since the rider rim makes for a more laterally stiff tire, you can drop tire pressures for a more supple ride which echoes what we’ve heard from other companies recently. According to Bontrager, some of their riders are still riding the same pressures (old habits die hard), but many have dropped pressures as a result.
The new Aeolus rim is not hookless but has a beefy shape thanks to its 31mm overall width. It’s crafted from Bontrager’s RSL-level OCLV carbon, a material they claim is some of the lightest and strongest carbon fiber available. While the wheels are assembled in the USA, the rims themselves are made overseas.
The Bontrager Aeolus RSL wheelset employs the same Bontrager-styled DT-240 EXP hubs as the RSL 37 version. The new DT-240 is a popular hub choice for bike manufacturers’ high-end wheels.
Bontrager’s take on the DT-240 EXP is one of my favorites thus far. They play up the flange and give a shield over the spoke head – this adds some cool extra styling that sets it apart from the sea of straight-pull aesthetics. They also use a unique straight pull spoke with a larger spoke head that wedges into the cutouts in the flange.
The hubs come stock with 12mm endcaps and a 11spd freehub body. For those curious, the end caps can be swapped for 15mm, and the freehub body is compatible with other Ratchet EXP freehubs like XDR.
Bontrager 3D modeling in real-world conditions.
Bontrager relied heavily on super computers to run the whole design process in 3D. Previously, they would start with a 2D process, and only move to 3D once they were closer to the final design due to computational constraints of doing the whole thing in 3D. Now though, the Bontrager team has the resources to start off using 3D CFD (Computational Fluid Dynamics) and letting the program run constantly for months, testing thousands of new iterations.
When Bontrager took the first prototypes to the wind tunnel, they claim the results were even better than what they were seeing in CFD. Like off the chart better. Better yet, Bontrager makes big claims by saying that they improved on both low yaw and high yaw conditions which usually has a trade off between the two.
Bontrager claims the wheels within the Aeolus RSL line are the fastest the team has yet to create. The claims are substantial, and the watt savings look suitable for all rim depths compared with the older Bontrager models. For example, the new Bontrager RSL 51 is 16% more aerodynamic than its predecessor, the Bontrager XXX 4 tubular and 9% more stable. The graphs speak for themselves; this rim profile is much fast than its predecessor, tubulars be damned.
Available Bontrager Aeolus RSL wheel models
Bontrager Aeolus RSL 51
Ride Profile: A versatile rim profile great for all conditions, sprinting, and climbing.
Weight: 1410g/set *claimed -1460g actual
Bontrager Aeolus RSL 62
Ride Profile: A rim profile suited to sprinters and crit racer alike.
Bontrager Aeolus RSL 75
Ride Profile: A depth best for triathlon, time trial riders, and crit monsters.
Weight: 1645g/set *claimed
Bontrager Aeolus RSL 37
Ride Profile: An ultralight 37mm rim profile for climbing and all-around riding.
Clincher only – Tubeless or Tubed
All Bontrager Aeolus RSL wheels are only offered as tubeless ready clinchers. As usual, the wheels include the plastic Bontrager TLR rims strips and tubeless valves, as well as a rim strip if you want to run tubes. You can also run tubeless tape instead of the strips if you want a lighter set up that’s a bit more involved to install.
All wheels come standard with axle end caps for 12mm thru axles, DT-Swiss 240 EXP hubs (SRAM XDR driver solid separately), Bontrager tubeless rim strips, and Bontrager alloy valve stems.
The wheelset carries Bontrager’s Carbon Care Wheel Loyalty Program. The program offers riders free replacement for any riding damage in the first two years of wheel ownership – Which is a great deal because these wheels are not cheap at $2,400 per pair.
Aerodynamics on a budget
Not everything that Bontrager released today is out of reach of the working class cyclist. The new super aerodynamic Aeolus shape made it to the line of workhorse aero Bontrager Aeolus Pro wheels.
The new Bontrager Aeolus 51 Pro wheel is the counterpart of the Aeolus 37 Pro launched with the RSL 37 last June. A very respectable build and with a similar rim – this wheelset could steal the show. Switching from RSL OCLV carbon to OCLV Pro Carbon, the Aeolus 51 Pro shares the same rim profile as its RSL brethren.
Bontrager Aeolus Pro 51
Ride Profile: Same versatile rim profile of the RSL 51 but at nearly half the cost
The hubset is a sturdy Bontrager build with12mm thru-axle DT-Swiss 350 internals and a 36 tooth star ratchet (and more standard nail-head straight pull spokes). The rim is tubeless-ready and boasts the same 23mm inner and 30mm outer as the RSL 51 wheelset.
The new Bontrager Aeolus Pro 51 wheelset weighs in at a claimed 1590g/set – nearly 200g heavier than the RSL 51 version. The build is robust, and it’s not always the wheel’s weight; it’s how it spins at speed. Maybe you can feel a little bit faster knowing you saved $1,100 for going with the Aeolus Pro over the RSL.
The Aeolus RSL and Aeolus Pro wheelsets are available for purchase now at your local Trek or Bontrager dealer.
Stay tuned for a full review of the Bontrager Aelous RSL 51 and 62 models.