Bontrager Aeolus XXX 4 TLR Disc Wheelset Review

Bontrager’s wheel program has long been heralded as among the best wheelsets on the market. While some so-called “house brands” have been simply rebadged designs, Trek’s dedicated wheel team spends a great deal of time developing their products. And, with the latest Bontrager Aeolus XXX wheelsets, you get hoops that have been proven at the highest levels of the sport with modern features the market demands. These are serious wheels for the most discerning riders.

Bontrager Aeolus XXX 4 Disc Wheelset Features:

• OCLV XXX premium carbon layup
• Rims are made in USA and wheels are assembled by hand in Waterloo, WI
• Speed Stability Shaping to reduce side force and allow deeper depths
• Center Lock disc brake hubs with front and rear 12mm thru-axles
• 47mm rim depth provides unmatched stability and confidence for an all-conditions aero wheel
• Tubeless Ready (TLR), with 21mm inner rim width for enhanced tire support (27mm external)
• DT Swiss internals for a buttery smooth ride feel and reliable 36-point star ratchet engagement
• Laser-etched graphics provide a fast, finished look with no added weight
• Includes TLR rim strip and valve stem along with traditional tube-type rim strip
• Weight: 715 grams (front), 810 grams (rear), 1525 grams (set) — actual weights
• MSRP: $2399.98 (pair)

Aggressive price, aggressive performance

While Bontrager doesn’t mess around with R&D and overall quality, they always sharpen their pencils and get their prices down to the best value possible. Here, we have a 47mm, disc-brake, carbon clincher that’s tubeless-compatible and replete with all the other technology you’d expect — all for an unmatched price. Nobody’s calling the XXX 4’s cheap, but dollar-for-dollar, I challenge you to find anything this good at $2400.

The rim profile of the 47mm XXX 4’s bucks the current snub-nose profile trend by going with more of a pointed shape. If you’re used to those stubby wheels we see so often, these will initially look “dated.” However, looking at the specs and experiencing their performance will tell you that these are anything but dated.

While we’re at it, let’s have a look at the shape of the XXX 4’s compared to the XXX 2 and XXX 6’s so you can see what I’m talking about. Yup, the profiles of the deeper wheels are decidedly more pointed than those from Zipp, HED, ENVE, Boyd, Alto and others. This was the result of thousands of Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD) simulations for optimal air flow and performance. That’s nerd technology for computer models and wind flow optimization. In their labs, the new XXX 4’s stack up better than Zipp and Enve.

For the full technical details, view the Aeolus XXX Whitepaper.

Tubeless or not — your choice

Bontrager has long been a proponent of tubeless road and that preaching continues with their latest XXX 2, 4 and 6 wheelsets. Their tubeless strategy is headlined by both a wide, 21mm internal width and their proprietary locking rim strips. Instead of just rim tape, these wheels include plastic strips that pop into place for a long-lasting airtight seal. My best pro tip for seating these strips is to place the tubeless valve and lock it in position before seating the rest of the strip. I also usually go back all the way around either side with my thumb to ensure it is full-seated as well (it will “click” into place).

Failing to get the valve in first could result in the liner being installed slightly off — believe me, even 1/8″ off is nearly impossible to fix without painstakingly removing the liner and starting over. Let me reiterate, removing that rim strip is really, really difficult and does add over 100 grams total. So, if you’re going tubeless, lock-and-load. If you’re going straight clincher, just use the included fabric rim strip for the lightest setup.

That said, once configured I installed a set of 28mm Bontrager AW2’s and seated them quickly using the Bontrager TLR Flash Charger tubeless pump. Even with the wide internal width of the XXX 4’s, the AW2’s only measured out to 28.6mm. The Pirelli PZero Velo 4S 28’s measure out to 30mm, so yeah, it goes without saying that tire measurements will vary. But these rims will generally allow a fuller, rounder and wider overall tire, so keep that in mind if frame tolerances are tight.

Tubeless tires vary in performance and notably, road feel. While the AW2’s were durable for all-season performance, they aren’t nearly as supple as the Pirelli PZero Velo’s with tubes. I spent about half my time on each setup and preferred the Pirellis overall, but the AW2’s are downright bombproof for winter riding.

And, don’t go thinking that Bontrager wheels are only for Trek bikes. They look quite sharp aboard the Factor O2 Disc as well as the Trek Emonda SLR. Either way, these wheels will be great on any top-shelf bike you mount them on.

Fast and confident everywhere

Where these specs and performance matter most is on the open road. At 47mm deep, the XXX 4’s sit on the fringes of crosswind comfort in my book. Utah’s powerful crosswinds tend to be problematic for deep-profile rims as they can grab your front wheel and turn a fast descent into a white-knuckle affair. Both the Zipp 303 and Zipp 454 NSW wheels are in the same ballpark here. Between those and the XXX 4’s, I’d put the XXX 4’s on par or slightly better at shrugging off crosswinds.

While Bontrager makes shallower wheels for climbing, the XXX 4’s can certainly hold their own. At 1525 grams, these are definitely respectable and won’t hold you back on even the steepest climbs. Outfitted with fast tires, you won’t point to the wheels as the reason for not nabbing that KOM (though I’d love a set of XXX 2’s for pure climbing).

Rolling terrain is also tackled with panache as these slice through the wind quite well. Aerodynamics are a tough metric to test in the wild, but they do feel fast and roll smooth. For optimal aerodynamics, 25mm tires are recommended. In my roll-to-stop tests that I do with all wheelsets, the XXX 4’s rolled to a stop among the best wheels I’ve tested. The Bontrager hubs feature DT Swiss internals and deliver quality, fast engagement.

Should you need any maintenance in the future, accessing the nipples is easy and spokes should be readily-available. Plus, the DT Swiss internals are the industry-standard and serviceable just about anywhere. Just to be sure you’re covered with your wheel investment, Bontrager does offer a 2-year no-questions-asked Carbon Care Program to replace damaged wheels. Beyond that timeframe, it’s a deep discount should anything catastrophic happen.

The Good

• Superb at shedding crosswinds
• Excellent overall depth
• Rims are made entirely in Waterloo, Wisconsin
• Laterally-stiff during the most demanding efforts
• Tubeless is a breeze
• Extra internal width makes for a fuller tire at lower pressures
• Long-lasting laser-etched graphics (except the XXX sticker)
• Centerlock rotors are the
• Freehub rolls nice and quiet
• Easily-sourced spokes and hub parts in the future

The Bad

• Install those TLR strips with care
• TLR strips add over 100 grams (but perform well)
• Must use wheel-specific tubeless valves (included)

The Bottom Line: Bontrager Aeolus XXX 4 TLR Disc

Bontrager spent considerable time and effort revising their already-stellar rims. The XXX 4’s represent some of the best all-around wheels on the market and they come in at a significantly-lower price than those from ENVE and Zipp. Yes, they are still a major investment, but my on-road experience puts these among the best at staving off pesky crosswinds and they roll fast on the flats.

Buy Now: Visit TrekBikes.com (or your local dealer)