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Let’s check ‘em out:
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As usual, we want the numbers.
Bontrager Aura 5 TLR Specs:
MSRP: $529.99 front, $669.99 rear, $1199.98 per pair
Construction: Aluminum rim with carbon fairing
Rim depth: 50mm
Rim width: 23mm outer, 17.5mm inner
Rim compatibility: Standard clincher and tubeless clincher
Weight: 760g front, 960g rear, 1720g pair
Rear hub compatibility: SRAM, Shimano, or Campagnolo 9/10/11-speed
Spokes: 18 front, 24 rear bladed
Includes quick release skewers, tubeless rim tape, standard rim tape, freehub shim, and tubeless valves
No rider weight limit
Here’s the accessory kit that comes with every Aura 5 TLR wheel set:
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MUST you use tubeless tires with these wheels? No. You can use standard clincher tires. In fact, that’s what I used for most of my testing, because Bontrager doesn’t yet have a 28mm wide tubeless road tire available (28’s are almost a necessity with Michigan pothole-laden roads; it’s really more like mountain biking).
As you can see, there are two sets of rim tape with the wheels (below). The white tape is for use with inner tubes, while the special black tape is for tubeless:
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The rim bed looks fairly standard with no tape installed; width is 23mm outside-to-outside, and 17.5 inside-to-inside. That puts it in the ‘wide-ish’ category these days. Expect that tires will run about 1mm wider-than-labeled with such a rim.
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Bontrager even prints the spoke lengths right on the rim. From mechanics around the world: Thank you, Bontrager!
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Bontrager supplies these very nice long tubeless valves with your wheels. They have removable cores, and don’t require the use of any extenders. A+.
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With the tubeless tape installed, the valve matches up nicely…
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Be sure to tighten down the nut on the other side. I was initially concerned that this may crack the carbon fairing, but so far, so good. The fairings seem thicker and more robust than, say, Hed’s latest Jet fairings – likely at a slight weight penalty.
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I installed my sealant in the exact same fashion as-shown in our RXL TLR review linked at the top of this article. A sealant injector or small 2 oz bottle of Bontrager TLR sealant makes the work easy.
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Tire fit was similar to the RXL wheels – which is to say, very tight. To this day, that is the biggest compromise I find with tubeless road clinchers. You can either have tight fit and the ability to inflate with a floor pump OR easy fit and the requirement of an air compressor for inflation. I have had a puncture on some (non-Bontrager) tubeless tires that did not seal successfully with sealant, and it took me about 15 minutes and great effort to install a tube. For racing, I’m sticking with tubes.
Here is my completed set with 700x25mm R3 tubeless tires:
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The tires measured right at 25mm when brand new. It’s not uncommon to get .5 – 1mm of growth over time.
Hubs are Bontrager’s own design with a minimal straight-pull front…
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…and 9/10/11-speed compatible rear hub.
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While some of Bontrager’s higher-end wheels have DT Swiss hub internals, these Aura 5’s feature a more standard (and lower-cost) 3-pawl design. Most hubs of this nature require lubrication of the freehub mechanism every six months or so with a medium weight oil.
During my test period, I found that some sort of oil or grease was leaking out of the left side after several rides:
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I inquired with Bontrager representatives about this, who responded:
“That’s [excess] grease from the underside endcap. As part of the manufacturing process, [we] put a ring of grease on top of the bearing before installing the endcap. This is done as an extra layer of protection for shipping and storage.”
The slow leak has not caused any issues, but I have had to clean it off several times.
How do these Aura 5’s stack up in the aero department? Similar to many other wheels today, they feature a fairing-type construction. I have yet to see any definitive evidence that this is any better or worse than a structural aero section in terms of aerodynamics.
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Bontrager reported to me that their testing was done at the San Diego Low Speed Wind Tunnel, which is widely known as one of the best test facilities for cycling-specific products in the world. They did a zero-to-twenty yaw sweep, and pitted their wheel against the Mavic Cosmic Carbone SL:
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Tests were performed on the same day, with the same Bontrager R3 700x23 tire, in the same orientation, at the same 120psi pressure. The test was front-wheel-only, with no bike or rider.
As the graph shows, the Bontrager clearly wins the test. However, I don’t personally consider it a true apples-to-apples comparison, as the Mavic has a much narrower 19mm rim. With a wide tire and narrow rim, it’s no surprise that the Mavic suffered. I’d also like to see more competitors in the 50mm depth range on this chart – the Hed Jet 5, Zipp 303, Reynolds’ 46, or perhaps a Vision TC50 (the list could go on).
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Are these Bontrager Aura 5’s for you? Specific to Trek, I think they fill a very nice niche – a good price point relative to most competitors, good aero performance, and the simplicity of aluminum braking surfaces. For owners of the Speed Concept, this is a great race wheel for someone that trains on Bontrager’s 23mm-wide RXL series wheels (eliminating the need for brake adjustments when swapping wheels).
I would love to see 70 or 80mm-deep version of this wheel. Many age group athletes ride front rims in the 40-60mm depth range for easy handling, but there’s little reason that they couldn’t use a deeper rear – and would benefit from the aerodynamic edge. I inquired with Bontrager about the possibility of such a wheel, but they were not able to confirm any plans.
Personally, I really enjoyed the Aura 5s. I have used them as my go-to trainers for several months now, and they haven’t missed a beat. There’s no brake rub, no noise, and nothing to complain about, save a little bit of oil on the rear/left end cap. With 28mm tires at about 70psi, they ride like a supercharged Cadillac on the streets of Detroit. I give ‘em a tip of the hat for overall performance, and will keep my fingers crossed for a deeper-rim version.