The Bontrager Aura 5 TLR road tubeless wheelset is a solid, all-around option for riders who want a single solution for everyday riding and perhaps a little competition.
With wide rims (18.5mm internal) optimised for 25mm tyres, an aluminium brake track, aero fairings and dependable hubs, the Aura 5 TLRs are a good value. While the weight (1,780g for the set) is competitive, having the spoke nipples buried in the rim under rim strips limits serviceability, and the flexible aero fairings feel a bit like a facade.
We tested the Aura 5 TLRs with Bontrager R3 25mm tyres. Although they're not as sprightly as a climbing wheelset, the wheels rev up to speed nicely. Out of the saddle, stiffness is adequate — no brake rubbing here — and the wheels don't ride harshly.
We made a point of giving the wheels a good thrashing to test both their integrity and how the tubeless tyre and seals would hold up. On New Year's Day, for example, we did a 112-mile group ride over many a washboarded dirt and gravel road through Native American pueblos in New Mexico.
Some of the particularly teeth-rattling sections caused flats for others. At least one rider also suffered a flat — and subsequently bailed on the rest of the ride — after a puncture from a goathead, a nasty little thorn common in New Mexico. With 30ml of sealant in our R3 tyres, however, we were able to merely flick an embedded goathead off our tyre without stopping.
At mile 75, we did sustain a 4mm tear on the rear tyre, but didn't need to stop; the sealant did its job as we kept rolling along in the group.
While small holes — from nails, goatheads or the like — are easily handled by Bontrager and other tubeless tyres with sealant, this 4mm size cut seemed to be borderline for having to eventually change the tyre. (The sealant formed a glob on the exterior of the tyre, as if we had chewing gum stuck to it. Pulling this glob off after the ride resulted in a fresh leak, which took a few minutes to seal.)
However, we were able to ride nearly 40 miles on it without anything more than a slight loss in pressure and some nasty spray on the back of the down tube. This is definitely preferable to having to stop and change an inner tube.
For smaller punctures, as mentioned above, the tubeless sealant is a godsend. On average, the 30ml of sealant you need per tyre is about 30g — a substantial saving over the average 120g tube. Granted, tubeless tyres will likely weigh a few more grams than standard clinchers, but you're still reducing rotating weight.
We blasted the wheels with a hose many times, and the hubs are still nice and silky smooth. The radially laced front wheel and 2x back wheel stayed fairly well in true over testing; we ended up with small ( 2mm) wobbles after a few months of often-rough treatment.
We wish the carbon fairing was a solid shell, however, with the spoke nipples mounted externally rather than buried in the rim. While Bontrager insists that the need for wheel truing is quite rare — and often done by a shop instead of the rider — we have been on more than one ride where somebody has broken a spoke, and being able to do a rough true on the road makes the difference between being able to ride it in and having to call for a ride. With the Aura 5 TLR, you have to take off the tyre, deal with the sealant spilling everywhere, peel off the plastic rim strips and then true the wheel.
Also, the pliable rim fairing doesn't make for a rock-solid anchor for the valve stem. It took three attempts to get the rear wheel to seal properly, with air leaking out at the valve stem. The front sealed immediately. And once the rear did seal, the valve seal was good for months, including through several tyre swaps.
The rim shell also has small gaps around each spoke, where water or general road grime can get in. There is a single relief hole closer to the brake track on either side of the rim.
Our only other gripe is the relative difficulty in mounting tyres onto the wheels. Compared to the Easton EA90 SLX tubeless wheels we recently tested, the Aura 5 TLRs are a bit of a wrestling match, regardless of which tyre you use.
Now, this initial mounting only happens once, but should you really tear the tyre beyond the sealant's capacity out on the road, you'll have to battle with it there to install a tube and perhaps a boot. Bontrager said the test sample we received had a slightly larger rim than spec, and that the production wheels should be easier to deal with.
Riding in the wind, the 50mm rims are stable and predictable. We were comfortable riding them in 30mph/48kph crosswinds. Make no mistake, you can certainly feel the wind on the rims, but the pressure doesn't change rapidly as it can with some sharper-edged rims.
Bontrager claims these wheels are faster than Mavic's Cosmic Carbone SLs. We did not test either in a wind tunnel. While not a direct comparison, Shimano's 50mm C50 wheels with a structural carbon cone and aluminium brake track weigh 90g less (1,692g/set) — but cost nearly twice as much.
All in all, these are good tubeless wheels for the price. A solid rim — internally and externally — with external nipples would make them a good wheelset.