New Bontrager Aeolus XXX aero wheels focus on stability, weight, and braking

by James Huang


Bontrager introduced its current range of Aeolus D3 carbon fiber aero road wheels back in 2011, and given the normally frenetic pace of change at this pointy end of the market, that seems like a lifetime ago. However, aerodynamic road wheel development had already grown very mature by that time, and it’s perhaps more a testament to the D3’s forward-looking design that it has still remained competitive today.

Nevertheless, Bontrager has now announced a replacement for the Aeolus D3 family, called Aeolus XXX. Naturally, Bontrager still claims that each new Aeolus XXX model is more aerodynamically efficient than similar wheels from competing brands, but speed isn’t the main story here; it’s increased crosswind stability and decreased weight. Rim-brake models also take a major step forward with a new sidewall surface treatment that Bontrager says brings carbon brake performance on-par with aluminum — even in the wet.


Story Highlights

  • 28mm, 47mm, and 60mm rim depths
  • Rim-brake and disc-brake versions
  • Clincher and tubular versions
  • Laser-machined brake track on rim-brake versions
  • 21mm-wide internal width and tubeless compatibility for clinchers
  • US$2,400 / AU$TBC / £2,000 / €2,400

Shallower, but faster

Bontrager has long gravitated toward roughly 30mm, 50mm, and 70mm section depths for its Aeolus aero road rims, but the new Aeolus XXX range moves to shallower profiles across the board. The 35mm-deep Aeolus D3 3 is now transitioning to the 28mm-deep Aeolus XXX 2; the 50mm Aeolus D3 5 becomes the 47mm Aeolus XXX 4; and the 70mm Aeolus D3 7 steps down to the 60mm Aeolus XXX 6.

Yet regardless of the decreases in section depth, Bontrager hints that all of the new wheels are more aerodynamic than the ones they replace, and perhaps more importantly from a consumer perspective, competitive with — or even faster than — similar wheels from other brands. For example, the Aeolus XXX 2 is said to be faster than Zipp’s 303 NSW (which is 17mm deeper), while the Aeolus XXX 4 is nearly on-par with the Zipp 404 NSW.

No comparisons were drawn between any Aeolus XXX wheelset and Zipp’s latest 454 NSW.

Bontrager Aeolus XXX wheels
Bontrager’s new Aeolus XXX rim profiles are notably less bulbous than some others on the market. Photo: Bontrager.

Either way, Bontrager says it isn’t just going for flat-out speed with its latest-generation aero road wheels (and given the maturity of the segment, it’s questionable how much is left to be gained there, anyway). While the aerodynamic claims are impressive given the decreases in section depth, it’s the associated benefits of those shallower profiles that are arguably more appealing.

Steady as she goes

Many aero wheel makers shifted years ago from all-out aerodynamic speed to improving crosswind stability, with Zipp being one of the most notable brands to pivot in that direction. Nothing improves performance in that area more than simply running a shallower wheel, however, and it’s here where Bontrager says its new wheels shine brightest. By coupling those section depth reductions with more refined shapes to maintain overall efficiency, Bontrager claims most Aeolus XXX riders can confidently “go up” a size for more speed without fear of having to leave them at home on a blustery day when they might otherwise opt for a shallower and more stable option from another brand.

Those shallower profiles obviously yield reductions in weight, too, and the specs are certainly enticing.

Bontrager Aeolus XXX wheels
Bontrager claims the new Aeolus XXX 2 (background) is more aerodynamic than Zipp’s 303 NSW, but yet is also 120g lighter and more manageable in crosswinds thanks to its shallower profile. Likewise, the Aeolus XXX 6 (foreground) is said to be faster than the Zipp 404 NSW, but also lighter, wider, and more stable.

Claimed weight for the new Aeolus XXX 2 clincher is just 1,305g as compared to 1,375g for the Zipp 202 NSW, with most of that difference coming from the rim, where it matters most. Claimed weight for the bare Aeolus XXX 2 hoop is 370g — 42g lighter than the 202 NSW, and 40g lighter than Enve’s 2.2.

Official weight for the Aeolus XXX 4 is a similarly svelte 1,400g, as compared to 1,425g for the Zipp 303 NSW and 1,526g for the Enve 4.5. And again, the biggest contributor to the difference in mass is the rim, with the Aeolus XXX 4 coming in at 430g, versus 458g for the 303 NSW and 469g for the 4.5.

That weight advantage mostly levels off at the deeper end of the spectrum, however. Bontrager says the Aeolus XXX 6 tips the scales at 1,530g — just 25g lighter for the full set relative to the Zipp 404 NSW, but with a nearly identical 500g rim weight. That’s still 20g lighter per rim than the Enve 6.7, but just 24g lighter for the set.

Wider yet, still tubeless-compatible

If you’re a fan of wider internal rim widths, though, Bontrager has all of those competitors handily beat. While the previous Aeolus D3 clinchers were already generously proportioned with 19.5mm of space between the bead hooks, the new Aeolus XXX goes wider still, now measuring a full 21mm across.

Bontrager says each Aeolus XXX rim has been optimized for 25c tires, although with such a broad mounting base, the effective measurement ends up being wider than the printed numbers might otherwise suggest. Actual width of a 25c Bontrager R4 on the new Aeolus XXX clincher is 26.5mm at 80psi, which plays well aerodynamically with each rim’s 27-28mm maximum external width.

Bontrager Aeolus XXX wheels
The 25c tires that Bontrager says are ideal for use with the new Aeolus XXX wheels puff up to almost 27mm when mounted on the 21mm-wide tire bed. But even with that extra width, the tire shape still seems to play nicely with the rim shape. Photo: Bontrager.

Otherwise, the usual benefits of wider tire beds still hold as true as ever, including improved casing support for more confident cornering, the ability to run lower pressures with less fear of casing squirm, and broader contact patches for improved traction. As a nice bonus, the closely-matched tire and rim widths mean that rim-brake users won’t have to bother opening up their brake calipers when it comes time for a wheel change, either.

https://cyclingtips.com/2016/11/the-new-normal-the-thinking-behind-wide-road-wheels/

As with the Aeolus D3, the Aeolus XXX maintains Bontrager’s commitment to tubeless compatibility, using the same system the company has championed since the mid-1990s. Unlike the paper-thin tapes preferred by much of the competition, Bontrager’s molded plastic tubeless rim strips are impressively tough and durable, and provide more exacting dimensions for better air retention, more consistent installation and removal, and confident bead security.

Bontrager Aeolus XXX wheels
The plastic rim strip includes ridges along either side of the tire bed, which helps lock the tire bead in place for extra security.

On the downside, each rim strip is also about 15g heavier than the equivalent length of tubeless tape, so some of the claimed weight advantage of the Aeolus XXX wheels goes away if you decide to go tube-free. Tube-type users will still reap the full benefit, though.

Reigning it in

There’s little question at this point that the road market is shifting toward disc brakes en masse, but even though they’re becoming increasingly common, they remain vastly outnumbered by rim brakes, if for no other reason than the decades of perfectly good rim-brake bikes that are still being used. Bontrager could very well have just carried on with its existing brake surface technology to ride out the transition until discs take full hold, but instead opted to keep advancing the segment with a new sidewall treatment called Laser Control Track.

As the name suggests, Laser Control Track features a laser machining process that strips away the outer layer of resin from the brake surface. The machining also adds a finely grained texture that Bontrager says works ideally with the included SwissStop Black Prince carbon-specific pads. The process is analogous to the 3Diamant treatment on Campagnolo Bora Ultra and Fulcrum Racing carbon wheels, which uses a diamond-tipped bit to similar effect.

Bontrager Aeolus XXX wheels Laser Control Track
The new laser-machined brake track is paired with SwissStop Black Prince pads for what Bontrager claims is quieter, more controllable, and more consistent than competitors’ carbon wheels.

Braking performance in dry conditions is only marginally improved as compared to the Aeolus D3, but there’s a major boost in wet conditions, according to in-house testing — so much so that Bontrager says the Aeolus XXX wheels will perform just as well as bare machined aluminum rims.

Bontrager will, of course, offer all of the new Aeolus XXX wheels in both rim-brake and disc-brake versions, however, along with both clincher and tubular versions across the board.

Bontrager Aeolus XXX wheels
The “stacked” lacing pattern on the driveside helps push the spokes further outboard as compared to a more traditional flange.

All of the new wheels are built with DT Swiss Aerolite bladed stainless steel spokes with custom aluminum nipples that are externally located for easier maintenance. Rear hubs continue to use proven DT Swiss Star Ratchet internals, with upgraded 36-tooth ratchet rings for more immediate power transfer as compared to stock 18-tooth drivers when you resume pedaling after coasting. Bontrager also continues to use so-called “stacked” lacing on the rear hubs to help improve bracing angles and overall wheel rigidity, and the aluminum hub shells now have gracefully contoured profiles that look more refined and upscale than the more cylindrical ones used on the Aeolus D3 range.

Pricing and availability

In a refreshing change from the norm, prices for the new Aeolus XXX wheels hold steady with the Aeolus D3, at US$2,400 / £2,000 / €2,400 for all models, regardless of depth or brake configuration; Australian pricing is still to be confirmed. All of the new wheels should also be available for purchase immediately as well — no waiting required.

In fact, we already have production sets of Aeolus XXX 2 and Aeolus XXX 6 rim-brake wheels on hand for review. It’s too soon for us to draw final conclusions, but early impressions are highly favorable, particularly in terms of braking performance. Claimed weights are almost exactly on target, too, with just 2g of variation from official figures. Stay tuned for more.

www.bontrager.com

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